styles.css

/* Reset & Base */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --font-ui: 'Source Sans 3', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-body: 'Lora', Georgia, ui-serif, serif;
    /* Main reading size (~17px at 16px root); was 1.125rem */
    --font-body-size: 1.0rem;
    --body-paragraph-gap: 1.0rem;
    --body-copy-width: 52rem;
    --media-copy-width: 56rem;
    --section-space-y: clamp(2rem, 4.8vw, 2rem);

    --bg-primary: #000000;
    --bg-secondary: #0a0a0a;
    --bg-card: #111111;
    --text-primary: #ffffff;
    --text-secondary: #e0e0e0;
    --accent-primary: #2563eb;
    --accent-secondary: #dc2626;
    --accent-gradient: linear-gradient(135deg, #2563eb 0%, #dc2626 100%);
    --border-color: rgba(255, 255, 255, 0.15);
    --success: #22c55e;
    --warning: #f59e0b;
    --error: #ef4444;
    --navbar-bg: rgba(10, 10, 15, 0.9);
    --navbar-bg-scrolled: rgba(10, 10, 15, 0.98);
    --chart-grid-color: rgba(255, 255, 255, 0.15);
    --chart-axis-color: rgba(255, 255, 255, 0.5);
    --chart-axis-text-color: rgba(255, 255, 255, 0.8);
    --chart-label-color: rgba(255, 255, 255, 0.9);
    --chart-marker-stroke: rgba(0, 0, 0, 0.3);
    --chart-annotation-color: rgba(255, 255, 255, 0.9);
    --chart-annotation-color-soft: rgba(255, 255, 255, 0.85);
    --chart-tooltip-bg: rgba(0, 0, 0, 0.85);
    --chart-tooltip-border: rgba(255, 255, 255, 0.16);
    --chart-tooltip-text: rgba(255, 255, 255, 0.95);
    --chart-tooltip-muted: rgba(255, 255, 255, 0.7);
    --overlay-panel-bg: rgba(12, 14, 22, 0.97);
    --overlay-panel-border: rgba(255, 255, 255, 0.12);
    --overlay-panel-text: rgba(240, 242, 250, 0.92);
    --overlay-panel-muted: rgba(255, 255, 255, 0.6);

    /* Dot-grid background texture: small dots on a regular grid */
    --paper-texture:
        url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='22' height='22'%3E%3Ccircle cx='11' cy='11' r='1' fill='white' fill-opacity='0.15'/%3E%3C/svg%3E");
}

body.theme-light {
    --bg-primary: #f5eddf;
    --bg-secondary: #ece0cf;
    --bg-card: #fbf4e9;
    --text-primary: #2f241a;
    --text-secondary: #645646;
    --accent-primary: #4f6cff;
    --accent-secondary: #b96c39;
    --accent-gradient: linear-gradient(135deg, #4f6cff 0%, #b96c39 100%);
    --border-color: rgba(79, 63, 44, 0.14);
    --navbar-bg: rgba(245, 237, 223, 0.9);
    --navbar-bg-scrolled: rgba(245, 237, 223, 0.98);
    --chart-grid-color: rgba(102, 82, 58, 0.12);
    --chart-axis-color: rgba(92, 73, 51, 0.38);
    --chart-axis-text-color: rgba(79, 63, 44, 0.82);
    --chart-label-color: rgba(60, 45, 31, 0.92);
    --chart-marker-stroke: rgba(85, 64, 42, 0.22);
    --chart-annotation-color: rgba(64, 48, 33, 0.9);
    --chart-annotation-color-soft: rgba(84, 65, 45, 0.84);
    --chart-tooltip-bg: rgba(251, 244, 233, 0.96);
    --chart-tooltip-border: rgba(110, 88, 60, 0.18);
    --chart-tooltip-text: rgba(47, 36, 26, 0.95);
    --chart-tooltip-muted: rgba(93, 76, 57, 0.74);
    --overlay-panel-bg: rgba(251, 244, 233, 0.97);
    --overlay-panel-border: rgba(110, 88, 60, 0.14);
    --overlay-panel-text: rgba(47, 36, 26, 0.92);
    --overlay-panel-muted: rgba(93, 76, 57, 0.74);
    --paper-texture:
        url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='22' height='22'%3E%3Ccircle cx='11' cy='11' r='1' fill='%23645646' fill-opacity='0.12'/%3E%3C/svg%3E");
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    background-color: var(--bg-primary);
    background-image: var(--paper-texture);
    color: var(--text-primary);
    line-height: 1.7;
    overflow-x: hidden;
    font-size: var(--font-body-size);
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background-color: var(--navbar-bg);
    background-image: var(--paper-texture);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
}

.nav-container {
    max-width: 1540px;
    margin: 0 auto;
    padding: 0.7rem 2rem;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
}

.nav-logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    text-decoration: none;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
    align-items: center;
}

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.95rem;
    font-family: var(--font-ui);
    font-weight: 400;
    letter-spacing: 0.03em;
    transition: color 0.3s ease, text-shadow 0.3s ease;
}

.nav-links a:hover {
    color: var(--text-primary);
    text-shadow:
        0 0 14px rgba(180, 205, 255, 0.48),
        0 0 28px rgba(120, 150, 255, 0.26),
        0 0 44px rgba(88, 118, 255, 0.14);
}

.nav-demo-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.22rem 0.58rem;
    border-radius: 999px;
    border: 1px solid rgba(138, 171, 255, 0.34);
    background:
        linear-gradient(135deg, rgba(255, 255, 255, 0.18) 0%, rgba(255, 255, 255, 0.06) 100%),
        linear-gradient(135deg, rgba(52, 112, 235, 0.98) 0%, rgba(126, 78, 236, 0.94) 100%);
    color: #fff;
    text-decoration: none;
    font-family: var(--font-ui);
    font-size: 0.9rem;
    font-weight: 600;
    letter-spacing: 0.01em;
    box-shadow:
        0 12px 30px rgba(52, 112, 235, 0.26),
        0 0 0 1px rgba(255, 255, 255, 0.08) inset,
        0 1px 0 rgba(255, 255, 255, 0.18) inset;
    backdrop-filter: blur(10px);
    transition: transform 0.2s ease, box-shadow 0.2s ease, filter 0.2s ease, border-color 0.2s ease;
    position: relative;
    overflow: hidden;
    white-space: nowrap;
}

.nav-demo-btn::before {
    content: '';
    position: absolute;
    inset: 1px;
    border-radius: inherit;
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.12), rgba(255, 255, 255, 0));
    pointer-events: none;
}

.nav-demo-btn:hover {
    transform: translateY(-1px);
    border-color: rgba(185, 210, 255, 0.58);
    box-shadow:
        0 18px 42px rgba(52, 112, 235, 0.38),
        0 0 22px rgba(118, 136, 255, 0.32),
        0 0 40px rgba(92, 102, 255, 0.18),
        0 1px 0 rgba(255, 255, 255, 0.22) inset;
    filter: brightness(1.1);
}

.theme-toggle-btn {
    position: absolute;
    right: 2rem;
    top: 50%;
    transform: translateY(-50%);
    display: inline-flex;
    align-items: center;
    gap: 0.48rem;
    padding: 0.36rem 0.7rem;
    border-radius: 999px;
    border: 1px solid var(--border-color);
    background: rgba(255, 255, 255, 0.06);
    color: var(--text-secondary);
    font-family: var(--font-ui);
    font-size: 0.88rem;
    font-weight: 600;
    letter-spacing: 0.02em;
    cursor: pointer;
    backdrop-filter: blur(10px);
    transition: color 0.2s ease, border-color 0.2s ease, background 0.2s ease, box-shadow 0.2s ease, transform 0.2s ease;
}

.theme-toggle-btn:hover {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.12);
    border-color: rgba(160, 190, 255, 0.28);
    box-shadow: 0 0 18px rgba(120, 150, 255, 0.14);
}

.theme-toggle-btn svg {
    width: 15px;
    height: 15px;
    display: block;
}

.back-to-top-btn {
    position: fixed;
    right: 1.6rem;
    bottom: 1.6rem;
    z-index: 960;
    width: 46px;
    height: 46px;
    border: 1px solid rgba(138, 171, 255, 0.26);
    border-radius: 999px;
    background:
        linear-gradient(135deg, rgba(255, 255, 255, 0.16) 0%, rgba(255, 255, 255, 0.05) 100%),
        linear-gradient(135deg, rgba(52, 112, 235, 0.92) 0%, rgba(126, 78, 236, 0.9) 100%);
    color: rgba(248, 250, 252, 0.96);
    box-shadow:
        0 14px 34px rgba(52, 112, 235, 0.22),
        0 0 0 1px rgba(255, 255, 255, 0.08) inset,
        0 1px 0 rgba(255, 255, 255, 0.16) inset;
    backdrop-filter: blur(12px);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transform: translateY(12px);
    pointer-events: none;
    transition:
        opacity 0.22s ease,
        visibility 0.22s ease,
        transform 0.22s ease,
        box-shadow 0.22s ease,
        filter 0.22s ease,
        border-color 0.22s ease;
}

.back-to-top-btn svg {
    width: 18px;
    height: 18px;
}

.back-to-top-btn.is-visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
    pointer-events: auto;
}

.back-to-top-btn:hover {
    border-color: rgba(185, 210, 255, 0.52);
    box-shadow:
        0 18px 40px rgba(52, 112, 235, 0.3),
        0 0 18px rgba(118, 136, 255, 0.24),
        0 0 0 1px rgba(255, 255, 255, 0.12) inset;
    filter: brightness(1.08);
}

.back-to-top-btn:focus-visible {
    outline: 2px solid rgba(185, 210, 255, 0.72);
    outline-offset: 3px;
}

.theme-toggle-icon--sun {
    display: none;
}

body.theme-light .theme-toggle-btn {
    background: rgba(110, 88, 60, 0.06);
}

body.theme-light .back-to-top-btn {
    border-color: rgba(110, 88, 60, 0.16);
    background:
        linear-gradient(135deg, rgba(255, 255, 255, 0.38) 0%, rgba(255, 255, 255, 0.16) 100%),
        linear-gradient(135deg, rgba(79, 108, 255, 0.88) 0%, rgba(143, 101, 224, 0.84) 100%);
    color: rgba(250, 248, 245, 0.98);
    box-shadow:
        0 12px 28px rgba(79, 108, 255, 0.14),
        0 10px 24px rgba(94, 76, 56, 0.08),
        0 0 0 1px rgba(255, 255, 255, 0.14) inset;
}

body.theme-light .back-to-top-btn:hover {
    border-color: rgba(110, 88, 60, 0.28);
    box-shadow:
        0 16px 34px rgba(79, 108, 255, 0.18),
        0 12px 28px rgba(94, 76, 56, 0.1),
        0 0 0 1px rgba(255, 255, 255, 0.18) inset;
}

@media (max-width: 720px) {
    .back-to-top-btn {
        right: 1rem;
        bottom: 1rem;
        width: 42px;
        height: 42px;
    }
}

body.theme-light .theme-toggle-icon--moon {
    display: none;
}

body.theme-light .theme-toggle-icon--sun {
    display: inline-flex;
}

body.theme-light .nav-demo-btn {
    color: #fff;
}

body.theme-light .navbar,
body.theme-light .hero,
body.theme-light .section-dark,
body.theme-light .footer {
    background-image: var(--paper-texture);
}

body.theme-light .trajectory-section {
    background-color: var(--bg-secondary);
    background-image:
        var(--paper-texture),
        radial-gradient(ellipse 110% 80% at 50% 108%, rgba(211, 189, 160, 0.28), transparent 56%),
        radial-gradient(ellipse 86% 52% at 18% 98%, rgba(200, 180, 155, 0.2), transparent 53%),
        radial-gradient(ellipse 90% 56% at 82% 98%, rgba(214, 195, 171, 0.22), transparent 54%),
        linear-gradient(185deg, #f3e9d8 0%, #eee1ce 42%, #eadcc8 72%, var(--bg-secondary) 100%);
}

body.theme-light .trajectory-section::before {
    opacity: 0.18;
}

body.theme-light .trajectory-section::after {
    opacity: 0.26;
    background:
        linear-gradient(to bottom, rgba(236, 224, 207, 0) 0%, rgba(236, 224, 207, 0.92) 100%),
        radial-gradient(ellipse 52% 34% at 12% 100%, rgba(180, 156, 128, 0.12), transparent 72%),
        radial-gradient(ellipse 46% 30% at 48% 100%, rgba(175, 149, 121, 0.1), transparent 68%),
        radial-gradient(ellipse 55% 36% at 88% 100%, rgba(188, 162, 136, 0.1), transparent 70%);
}

body.theme-light .trajectory-card,
body.theme-light .results-bar-chart,
body.theme-light .citation-box,
body.theme-light .method-video-wrapper,
body.theme-light .solver-vid-wrap,
body.theme-light .coverflow-frame {
    background: var(--bg-card);
    border-color: rgba(79, 63, 44, 0.1);
    box-shadow: 0 16px 36px rgba(94, 76, 56, 0.08);
}

body.theme-light .trajectory-canvas-wrap {
    background: linear-gradient(180deg, rgba(251, 244, 233, 0.98), rgba(241, 232, 217, 0.98));
    border-color: rgba(79, 63, 44, 0.08);
}

body.theme-light .solver-compare-note,
body.theme-light .trajectory-card-note,
body.theme-light .pca-scatter-hint,
body.theme-light .solver-label,
body.theme-light .coverflow-caption,
body.theme-light .form-note {
    color: rgba(83, 69, 54, 0.72);
}

body.theme-light .quote p,
body.theme-light .arch-quote p,
body.theme-light .section-title {
    color: var(--text-primary);
}

body.theme-light .hero-authors-popover,
body.theme-light .pca-hud-reset,
body.theme-light .pca-hud-filters,
body.theme-light .pca-point-tooltip {
    background: var(--overlay-panel-bg);
    border-color: var(--overlay-panel-border);
    color: var(--overlay-panel-text);
    box-shadow: 0 16px 40px rgba(94, 76, 56, 0.12);
}

body.theme-light .hero-authors-legend,
body.theme-light .meta-label,
body.theme-light .pca-hud-filters-title,
body.theme-light .pca-scatter-hint-sub,
body.theme-light .tooltip-label {
    color: var(--overlay-panel-muted);
}

body.theme-light .hero-authors-legend,
body.theme-light .hero-affil-block {
    border-color: rgba(110, 88, 60, 0.12);
}

body.theme-light .hero-authors-legend-i,
body.theme-light .hero-authors-list,
body.theme-light .hero-author-marks,
body.theme-light .hero-affil-block,
body.theme-light .hero-affil-block sup,
body.theme-light .pca-hud-filter-row,
body.theme-light .pca-scatter-legend,
body.theme-light .pca-legend-label,
body.theme-light .pca-point-tooltip-coords,
body.theme-light .pca-point-tooltip-src,
body.theme-light .results-bar-panel-title,
body.theme-light .results-bar-legend,
body.theme-light .bar-label,
body.theme-light .tooltip-row,
body.theme-light .tooltip-value {
    color: var(--overlay-panel-text);
}

body.theme-light .pca-scatter-canvas--loading::before {
    color: var(--text-secondary);
}

body.theme-light .pca-scatter-canvas--loading::after {
    border-color: rgba(110, 88, 60, 0.14);
    border-top-color: rgba(110, 88, 60, 0.42);
}

body.theme-light .results-bar-tooltip {
    background: var(--chart-tooltip-bg);
    border-color: var(--chart-tooltip-border);
    color: var(--chart-tooltip-text);
    box-shadow: 0 10px 24px rgba(94, 76, 56, 0.12);
}

body.theme-light .phy-video-card figcaption,
body.theme-light .citation-copy-btn {
    color: var(--text-primary);
}

body.theme-light .citation-copy-btn:hover {
    color: var(--text-primary);
    background: rgba(110, 88, 60, 0.08);
}

/* Hero Section */
.hero {
    min-height: auto;
    padding: 5.5rem 2rem 2rem;
    position: relative;
    background-color: var(--bg-primary);
    background-image: var(--paper-texture);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
}

.hero-content {
    max-width: 1320px;
    text-align: left;
    margin: 0 auto 2rem;
}

.hero-badge {
    display: inline-flex;
    flex-direction: column;
    gap: 0.25rem;
    margin-bottom: 1rem;
}

.badge-text {
    font-size: 0.9rem;
    color: var(--text-secondary);
    letter-spacing: 0.05em;
    text-transform: uppercase;
}

.badge-highlight {
    font-size: 1.15rem;
    font-weight: 600;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-title {
    margin-bottom: 1.5rem;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
    background: none;
    -webkit-text-fill-color: initial;
}

.title-name-wrap {
    position: relative;
    display: block;
    width: 100%;
    isolation: isolate;
}

.title-fx-canvas {
    position: absolute;
    left: -0.15rem;
    right: -0.15rem;
    top: -0.2rem;
    bottom: -0.08rem;
    width: calc(100% + 0.3rem);
    height: calc(100% + 0.28rem);
    pointer-events: none;
    z-index: 0;
    opacity: 1;
}

.title-name {
    display: block;
    position: relative;
    z-index: 1;
    font-family: 'EB Garamond', Georgia, serif;
    font-size: clamp(3rem, 7vw, 5.5rem);
    font-weight: 700;
    line-height: 1.0;
    color: var(--text-primary);
    letter-spacing: -0.01em;
}

.title-desc {
    display: block;
    font-family: var(--font-ui);
    font-size: clamp(1rem, 2vw, 1.35rem);
    font-weight: 400;
    line-height: 1.5;
    color: #aaaaaa;
    letter-spacing: 0.01em;
}

/* Hero title: hover / focus shows full author list */
.hero-title-interactive {
    position: relative;
    display: block;
    width: fit-content;
    max-width: 100%;
    cursor: help;
    outline: none;
    border-radius: 4px;
}

/* Invisible bridge so the pointer can reach the popover without losing hover */
.hero-title-interactive::after {
    content: '';
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    height: 0.75rem;
    z-index: 1499;
}

@media (hover: hover) {
    .hero-title-interactive:hover::after,
    .hero-title-interactive:focus-within::after {
        display: block;
    }
}

@media (hover: none) {
    .hero-title-interactive:focus-within::after {
        display: block;
    }
}

.hero-title-interactive:focus-visible {
    box-shadow: 0 0 0 2px rgba(120, 180, 255, 0.45);
}

.hero-authors-popover {
    position: absolute;
    left: 0;
    top: calc(100% + 0.75rem);
    z-index: 1500;
    min-width: min(100%, 320px);
    max-width: min(520px, calc(100vw - 2.5rem));
    max-height: min(70vh, 560px);
    overflow-x: hidden;
    overflow-y: auto;
    padding: 1rem 1.15rem 1.1rem;
    background: rgba(12, 14, 22, 0.97);
    border: 1px solid rgba(255, 255, 255, 0.12);
    border-radius: 12px;
    box-shadow: 0 16px 48px rgba(0, 0, 0, 0.55);
    backdrop-filter: blur(12px);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-6px);
    pointer-events: none;
    transition:
        opacity 0.2s ease,
        transform 0.2s ease,
        visibility 0.2s;
}

@media (hover: hover) {
    .hero-title-interactive:hover .hero-authors-popover,
    .hero-title-interactive:focus-within .hero-authors-popover {
        opacity: 1;
        visibility: visible;
        transform: translateY(0);
        pointer-events: auto;
    }
}

@media (hover: none) {
    .hero-title-interactive:focus-within .hero-authors-popover {
        opacity: 1;
        visibility: visible;
        transform: translateY(0);
        pointer-events: auto;
    }
}

.hero-authors-legend {
    margin: 0 0 0.65rem;
    padding-bottom: 0.55rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    font-family: var(--font-ui);
    font-size: 0.72rem;
    line-height: 1.45;
    color: rgba(255, 255, 255, 0.5);
    letter-spacing: 0.02em;
}

.hero-authors-legend-i {
    color: rgba(255, 255, 255, 0.75);
    font-weight: 600;
}

.hero-authors-sep {
    margin: 0 0.35rem;
    opacity: 0.5;
}

.hero-authors-list {
    margin: 0;
    padding: 0;
    list-style: none;
    font-family: var(--font-ui);
    font-size: 0.82rem;
    line-height: 1.55;
    color: rgba(240, 242, 250, 0.92);
    column-count: 1;
}

.hero-authors-list li {
    padding: 0.12rem 0;
    break-inside: avoid;
}

.hero-author-marks {
    margin-left: 0.2rem;
    font-size: 0.72em;
    color: rgba(180, 200, 230, 0.85);
    font-weight: 500;
    white-space: nowrap;
}

.hero-author-marks sup {
    margin-left: 0.08em;
    font-size: 0.85em;
    vertical-align: super;
}

.hero-affil-block {
    margin-top: 0.75rem;
    padding-top: 0.65rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    font-family: var(--font-ui);
    font-size: 0.78rem;
    line-height: 1.55;
    color: rgba(200, 210, 230, 0.88);
}

.hero-affil-block p {
    margin: 0.2rem 0;
}

.hero-affil-block sup {
    margin-right: 0.25em;
    font-size: 0.8em;
    color: rgba(150, 190, 230, 0.95);
}

@media (min-width: 520px) {
    .hero-authors-list {
        column-count: 2;
        column-gap: 1.25rem;
    }
}

.hero-meta {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 0;
    padding: 0.5rem 0;
    width: 100%;
    max-width: 418px;
    margin: 0;
}

.meta-item {
    display: flex;
    flex-direction: row;
    align-items: baseline;
    gap: 0;
    padding: 0.13rem 0;
    width: 100%;
}

.meta-label {
    font-size: 0.78rem;
    font-family: var(--font-ui);
    font-weight: 600;
    color: rgba(255,255,255,0.45);
    text-transform: uppercase;
    letter-spacing: 0.12em;
    min-width: 110px;
    flex-shrink: 0;
}

.meta-value {
    font-size: 1.0625rem;
    color: var(--text-primary);
}

.meta-link {
    font-size: 1.0625rem;
    font-weight: 400;
    color: var(--text-primary);
    text-decoration: none;
    border-bottom: 1px solid rgba(255,255,255,0.3);
    transition: border-color 0.2s ease, color 0.2s ease;
}

.meta-link:hover {
    color: var(--text-primary);
    border-bottom-color: var(--text-primary);
}

.hero-social {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
}

.social-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.social-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.85rem;
    padding: 0.25rem 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    transition: all 0.3s ease;
}

.social-link:hover {
    border-color: var(--accent-primary);
    color: var(--accent-primary);
}

/* Video in Hero */
.video-container {
    max-width: 1320px;
    width: 100%;
    margin: 0 auto;
}

.video-wrapper {
    width: 100%;
    aspect-ratio: 16/9;
    background: var(--bg-card);
    border-radius: 16px;
    overflow: hidden;
    border: 2px solid var(--border-color);
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4);
    position: relative;
}

.demo-video {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

/* Hide video until first-frame poster is captured (avoids black flash while large file buffers) */
.video-wrapper:not(.demo-poster-ready) .demo-video {
    opacity: 0;
}

.video-wrapper.demo-poster-ready .demo-video {
    opacity: 1;
    transition: opacity 0.28s ease;
}

/* ── Unified Video Player Controls ── */

/* Center play/pause button (appears on hover or when paused) */
.vid-center-btn {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: rgba(0, 0, 0, 0.55);
    backdrop-filter: blur(6px);
    border: 1.5px solid rgba(255, 255, 255, 0.6);
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    opacity: 0;
    transition: opacity 0.2s ease, transform 0.2s ease;
    z-index: 3;
    pointer-events: none;
}

.vid-center-btn svg {
    width: 22px;
    height: 22px;
}

/* Show center button when paused or on hover */
.video-wrapper:hover .vid-center-btn {
    opacity: 1;
    pointer-events: auto;
}

.vid-center-btn:hover {
    transform: translate(-50%, -50%) scale(1.08);
    background: rgba(0, 0, 0, 0.7);
}

/* Icon state: hide pause icon by default, show when is-playing */
.vid-center-btn .pause-icon,
.video-controls .pause-icon { display: none; }

.video-wrapper.is-playing .vid-center-btn .pause-icon,
.video-wrapper.is-playing .video-controls .pause-icon { display: inline-flex; }

.video-wrapper.is-playing .vid-center-btn .play-icon,
.video-wrapper.is-playing .video-controls .play-icon { display: none; }

/* When playing, hide center button unless hovering */
.video-wrapper.is-playing .vid-center-btn { opacity: 0; pointer-events: none; }
.video-wrapper.is-playing:hover .vid-center-btn { opacity: 1; pointer-events: auto; }

/* Mute icon state */
.mute-off-icon { display: none; }

/* Bottom control bar */
.video-controls {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    padding: 2rem 1rem 0.65rem;
    background: linear-gradient(transparent, rgba(0, 0, 0, 0.75));
    opacity: 0;
    transition: opacity 0.2s ease;
    z-index: 2;
}

.video-wrapper:hover .video-controls { opacity: 1; }

/* Progress bar */
.video-controls .progress-bar {
    height: 2px;
    background: rgba(255, 255, 255, 0.25);
    border-radius: 1px;
    cursor: pointer;
    position: relative;
    overflow: hidden;
    margin-bottom: 0.5rem;
    transition: height 0.15s ease;
}

.video-controls:hover .progress-bar { height: 3px; }

.progress-filled {
    position: absolute;
    top: 0; left: 0;
    height: 100%;
    background: rgba(255, 255, 255, 0.9);
    width: 0%;
    border-radius: 1px;
    transition: width 0.1s linear;
    pointer-events: none;
}

/* Bottom row */
.vid-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.vid-left, .vid-right {
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

/* Small icon buttons */
.vid-btn {
    background: none;
    border: none;
    color: rgba(255, 255, 255, 0.85);
    cursor: pointer;
    padding: 3px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: 3px;
    transition: color 0.15s ease;
    line-height: 0;
}

.vid-btn svg { width: 16px; height: 16px; }
.vid-btn:hover { color: #ffffff; }

/* Time display */
.vid-time {
    font-size: 0.72rem;
    font-family: var(--font-ui);
    color: rgba(255, 255, 255, 0.75);
    letter-spacing: 0.03em;
    line-height: 1;
}

/* Volume slider */
.vid-volume-slider {
    width: 64px;
    height: 2px;
    -webkit-appearance: none;
    appearance: none;
    background: rgba(255, 255, 255, 0.3);
    border-radius: 1px;
    outline: none;
    cursor: pointer;
    vertical-align: middle;
}

.vid-volume-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.9);
    cursor: pointer;
}

.vid-volume-slider::-moz-range-thumb {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.9);
    cursor: pointer;
    border: none;
}

.video-placeholder {
    aspect-ratio: 21/9;
    background: var(--bg-card);
    border-radius: 16px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 1.5rem;
    border: 2px solid var(--border-color);
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4);
}

.video-icon {
    width: 100px;
    height: 100px;
    background: linear-gradient(135deg, #2563eb 0%, #dc2626 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    color: white;
    cursor: pointer;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    box-shadow: 0 10px 30px rgba(37, 99, 235, 0.4);
}

.video-icon:hover {
    transform: scale(1.1);
    box-shadow: 0 15px 40px rgba(37, 99, 235, 0.6);
}

.video-placeholder p {
    font-size: 1.5rem;
    color: var(--text-primary);
    font-weight: 500;
}

.video-hint {
    font-size: 1rem;
    color: var(--text-secondary);
    max-width: 660px;
    text-align: center;
    line-height: 1.6;
}

/* Sections */
.section {
    padding: var(--section-space-y) 2rem;
}

.section-dark {
    background-color: var(--bg-secondary);
    background-image: var(--paper-texture);
}

.container {
    max-width: 1320px;
    margin: 0 auto;
}

.section-title {
    font-family: 'EB Garamond', Georgia, serif;
    font-size: clamp(1.8rem, 3.15vw, 2.45rem);
    font-weight: 500;
    line-height: 1.1;
    margin: 0 0 0.95rem;
    text-align: center;
    letter-spacing: -0.01em;
}

.subsection-title {
    font-family: var(--font-ui);
    font-size: 1.02rem;
    font-weight: 500;
    line-height: 1.4;
    color: var(--text-secondary);
    text-align: center;
    margin-bottom: 1.35rem;
    letter-spacing: 0.02em;
}

.coming-soon-badge {
    display: inline-block;
    margin-left: 0.5em;
    padding: 0.15em 0.6em;
    border: 1px solid currentColor;
    border-radius: 4px;
    font-size: 0.6em;
    font-weight: 400;
    opacity: 0.55;
    letter-spacing: 0.04em;
    vertical-align: middle;
}

/* Long-form body: Lora (calligraphic skeleton, slight hand-drawn warmth) */
.arch-description,
.method-text p,
.section-desc,
.highlight-text {
    font-family: var(--font-body);
    font-weight: 400;
    font-optical-sizing: auto;
    font-feature-settings: 'kern' 1, 'liga' 1;
    text-rendering: optimizeLegibility;
}

/* Long-form narrative paragraphs only */
.arch-description,
.method-text p,
.section-desc {
    text-align: justify;
    text-justify: inter-word;
}

.section-desc {
    color: var(--text-secondary);
    max-width: var(--body-copy-width);
    margin: 0 auto var(--body-paragraph-gap);
    font-size: var(--font-body-size);
    line-height: 1.78;
}

/* Architecture Section */
.architecture-content {
    text-align: center;
    margin-bottom: 0.75rem;
}

.arch-quote {
    border: none;
    padding: 0;
    margin-bottom: 2rem;
}

.arch-quote p {
    font-family: 'EB Garamond', Georgia, serif;
    font-size: 1.9rem;
    font-style: italic;
    font-weight: 400;
    color: var(--text-primary);
    margin-bottom: 0.4rem;
}

.arch-quote cite {
    font-size: 0.875rem;
    font-family: var(--font-ui);
    color: var(--text-secondary);
    font-style: normal;
    letter-spacing: 0.06em;
}

.arch-description {
    font-size: var(--font-body-size);
    color: var(--text-secondary);
    max-width: min(var(--body-copy-width), 92vw);
    margin: 0 auto var(--body-paragraph-gap);
    line-height: 1.78;
    text-align: justify;
    text-justify: inter-word;
    hyphens: auto;
}

/* Newspaper-style drop cap for long-form intro paragraphs */
.architecture-content .arch-description::first-letter {
    font-size: 1.1em;
    font-weight: 600;
}

/* ── Kai0-style task coverflow (center large, sides small) — distinct from solver-gallery ── */
.kai-task-reel {
    margin-top: 2.5rem;
    margin-bottom: 2.2rem;
    padding: 0;
}

.kai-task-reel .kai-task-lead {
    margin-bottom: 2.4rem;
    text-align: center;
    text-wrap: balance;
}

.coverflow-scene {
    position: relative;
    width: 100%;
    max-width: 1180px;
    margin: 0 auto;
    padding: 1.25rem 0 1rem;
}

.coverflow-viewport {
    position: relative;
    width: 100%;
    min-height: min(52vw, 420px);
    height: 52vw;
    max-height: 460px;
    perspective: 1200px;
    perspective-origin: 50% 45%;
    overflow: visible;
    margin-top: 0.35rem;
}

@media (min-width: 900px) {
    .coverflow-viewport {
        height: 420px;
        min-height: 420px;
    }
}

.coverflow-track {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    transform-style: preserve-3d;
    /* subtle ambient tilt */
    transform: rotateX(2deg);
}

.coverflow-slide {
    position: absolute;
    left: 50%;
    top: 50%;
    width: min(78vw, 760px);
    max-width: 760px;
    transition:
        transform 0.65s cubic-bezier(0.22, 0.9, 0.25, 1),
        opacity 0.45s ease,
        filter 0.45s ease;
    transform-origin: center center;
    will-change: transform;
    cursor: grab;
    user-select: none;
    -webkit-user-drag: none;
}

.coverflow-slide:active {
    cursor: grabbing;
}

@media (prefers-reduced-motion: reduce) {
    .coverflow-slide {
        transition-duration: 0.01ms;
    }
}

.coverflow-frame {
    position: relative;
    width: 100%;
    max-width: 760px;
    margin: 0 auto;
    aspect-ratio: 16 / 9;
    border-radius: 14px;
    overflow: hidden;
    background: #0a0c12;
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow:
        0 24px 70px rgba(0, 0, 0, 0.55),
        0 0 0 1px rgba(255, 255, 255, 0.06) inset;
}

.coverflow-vid {
    display: block;
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.coverflow-yt {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    border: 0;
    display: block;
}

.coverflow-speed-badge {
    position: absolute;
    left: 0.65rem;
    bottom: 0.65rem;
    z-index: 2;
    padding: 0.22rem 0.5rem;
    border-radius: 999px;
    background: rgba(0, 0, 0, 0.56);
    border: 1px solid rgba(255, 255, 255, 0.2);
    color: rgba(245, 248, 255, 0.95);
    font-family: 'Inter', sans-serif;
    font-size: 0.68rem;
    font-weight: 600;
    letter-spacing: 0.01em;
    line-height: 1;
    pointer-events: none;
}

body.theme-light .coverflow-speed-badge {
    background: rgba(250, 247, 240, 0.88);
    border-color: rgba(80, 68, 50, 0.25);
    color: rgba(58, 46, 34, 0.95);
}

/* Center: dominant */
.coverflow-slide.pos-center {
    z-index: 4;
    opacity: 1;
    filter: brightness(1.05) saturate(1.05);
    transform: translate(-50%, -50%) translateZ(48px) scale(1.08) rotateY(0deg);
}

/* Sides: smaller, recede, rotated */
.coverflow-slide.pos-left {
    z-index: 2;
    opacity: 0.82;
    filter: brightness(0.7) saturate(0.85);
    transform: translate(-50%, -50%) translateZ(-20px) translateX(calc(-42% - 18px)) scale(0.62) rotateY(18deg);
}

.coverflow-slide.pos-right {
    z-index: 2;
    opacity: 0.82;
    filter: brightness(0.7) saturate(0.85);
    transform: translate(-50%, -50%) translateZ(-20px) translateX(calc(42% + 18px)) scale(0.62) rotateY(-18deg);
}

/* Narrow screens: reduce horizontal offset */
@media (max-width: 640px) {
    .coverflow-slide {
        width: 92vw;
    }
    .coverflow-slide.pos-left {
        transform: translate(-50%, -50%) translateZ(-10px) translateX(-28%) scale(0.55) rotateY(14deg);
    }
    .coverflow-slide.pos-right {
        transform: translate(-50%, -50%) translateZ(-10px) translateX(28%) scale(0.55) rotateY(-14deg);
    }
}

.coverflow-caption {
    margin: 0.75rem 0 0;
    text-align: center;
    font-family: var(--font-ui);
    font-size: 0.82rem;
    font-weight: 600;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: rgba(255, 255, 255, 0.5);
}

.coverflow-slide.pos-center .coverflow-caption {
    color: rgba(255, 255, 255, 0.78);
}

/* Left/right tap targets only; center band stays free for swipe on the reel */
.coverflow-hits {
    position: absolute;
    inset: 0;
    z-index: 8;
    pointer-events: none;
}

.coverflow-hit {
    position: absolute;
    top: 0;
    bottom: 0;
    border: none;
    padding: 0;
    margin: 0;
    width: 38%;
    max-width: 320px;
    background: transparent;
    cursor: pointer;
    pointer-events: auto;
}

.coverflow-hit-left {
    left: 0;
}

.coverflow-hit-right {
    right: 0;
}

.coverflow-hit:focus-visible {
    outline: 2px solid rgba(120, 180, 255, 0.65);
    outline-offset: -2px;
}

/* Video Gallery */
/* ── Solver Gallery (pi0-style horizontal reel) ── */
.solver-gallery {
    margin-top: 1.4rem;
    position: relative;
    /* extend edge-to-edge beyond the section container */
    width: 106.5vw;
    left: 50%;
    transform: translateX(-50%);
}

/* Fade mask on right edge only (left has no overflow at start) */
.solver-gallery::after {
    content: '';
    position: absolute;
    top: 0;
    bottom: 28px;
    right: 0;
    width: 80px;
    z-index: 2;
    pointer-events: none;
    background: linear-gradient(to left, var(--bg-primary) 0%, transparent 100%);
}
/* Left mask pinned to global viewport left edge */
.solver-gallery::before {
    content: '';
    position: fixed;
    top: 0;
    bottom: 0;
    left: 0;
    width: 80px;
    z-index: 2;
    pointer-events: none;
    background: linear-gradient(to right, var(--bg-primary) 0%, transparent 100%);
}

/* Nav buttons row (below the reel) */
.solver-nav-row {
    /* fully decoupled from gallery width/offset */
    width: 100vw;
    margin-left: calc(50% - 50vw);
    display: flex;
    justify-content: center;
    gap: 0.6rem;
    padding: 0rem 0 0;
}

.solver-nav-btn {
    width: 34px;
    height: 34px;
    border-radius: 50%;
    border: 1px solid rgba(255, 255, 255, 0.18);
    background: rgba(12, 12, 18, 0.6);
    color: rgba(255, 255, 255, 0.65);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}
.solver-nav-btn svg { width: 14px; height: 14px; }
.solver-nav-btn:hover {
    background: rgba(40, 40, 55, 0.9);
    border-color: rgba(255, 255, 255, 0.35);
    color: #fff;
}

body.theme-light .solver-nav-btn {
    border-color: rgba(110, 88, 60, 0.16);
    background: rgba(245, 237, 223, 0.9);
    color: rgba(92, 73, 51, 0.72);
    box-shadow: 0 4px 14px rgba(94, 76, 56, 0.06);
}

body.theme-light .solver-nav-btn:hover {
    background: rgba(239, 228, 211, 0.98);
    border-color: rgba(110, 88, 60, 0.28);
    color: rgba(53, 40, 28, 0.92);
}

.solver-reel {
    display: flex;
    gap: 14px;
    overflow-x: auto;
    padding-top: 2px;
    padding-right: 2rem;
    padding-bottom: 12px;
    padding-left: max(2rem, calc((100vw - 1144px) / 2));
    scroll-padding-left: max(2rem, calc((100vw - 1144px) / 2));
    scroll-snap-type: x mandatory;
    cursor: grab;
    scrollbar-width: none;
    -webkit-overflow-scrolling: touch;
}

.solver-reel::-webkit-scrollbar { display: none; }
.solver-reel.is-dragging { cursor: grabbing; user-select: none; }

.solver-card {
    flex: 0 0 462px;
    scroll-snap-align: start;
}

.solver-vid-wrap {
    aspect-ratio: 16/9;
    border-radius: 10px;
    overflow: hidden;
    background: var(--bg-card);
    position: relative;
}

.solver-vid-wrap video {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

/* HD load: unobtrusive ring bottom-right (adaptive loading) */
.video-hq-ring {
    position: absolute;
    right: 8px;
    bottom: 8px;
    z-index: 4;
    width: 22px;
    height: 22px;
    pointer-events: none;
    opacity: 0;
    transition: opacity 0.22s ease;
}

.video-hq-ring.is-visible {
    opacity: 1;
}

.video-hq-ring svg {
    display: block;
    width: 100%;
    height: 100%;
    filter: drop-shadow(0 1px 2px rgba(0, 0, 0, 0.45));
}

.video-hq-ring-prog {
    transition: stroke-dashoffset 0.12s ease;
}

.video-hq-ring--pulse svg {
    animation: video-hq-ring-spin 0.85s linear infinite;
    transform-origin: center;
}

@keyframes video-hq-ring-spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

body.theme-light .video-hq-ring-prog {
    stroke: rgba(30, 30, 35, 0.72) !important;
}

body.theme-light .video-hq-ring-track {
    stroke: rgba(30, 30, 35, 0.14) !important;
}

/* ── Video badge (bottom-left): "3x autonomous" (only for zip videos) ── */
.zip-video-badge::after {
    content: "3x autonomous";
    white-space: nowrap;
    position: absolute;
    left: 12px;
    bottom: 12px;
    z-index: 5;
    padding: 6px 10px;
    border-radius: 10px;
    font-family: var(--font-ui);
    font-size: 12px;
    font-weight: 600;
    line-height: 1.1;
    letter-spacing: 0.02em;
    color: rgba(255, 255, 255, 0.92);
    background: rgba(0, 0, 0, 0.45);
    border: 1px solid rgba(255, 255, 255, 0.12);
    backdrop-filter: blur(6px);
    pointer-events: none;
}

.solver-label {
    margin: 0.55rem 0 0;
    font-family: var(--font-ui);
    font-size: 0.8rem;
    font-weight: 500;
    color: rgba(255, 255, 255, 0.5);
    letter-spacing: 0.02em;
}

/* ── Interactive 3D PCA scatter (Three.js) ── */
.pca-viz-section {
    padding-top: var(--section-space-y);
    padding-bottom: var(--section-space-y);
}

.pca-scatter-stage {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0;
    margin-top: 1.35rem;
}

.pca-scatter-view-wrap {
    width: 68%;
    max-width: 760px;
    margin-left: auto;
    margin-right: auto;
}

.pca-scatter-canvas {
    width: 100%;
    min-width: 0;
    min-height: 360px;
    border-radius: 12px;
    overflow: hidden;
    border: 1px solid rgba(255, 255, 255, 0.08);
    background: linear-gradient(165deg, #06080f 0%, #0c1018 50%, #080a10 100%);
    position: relative;
}

.pca-scatter-hud {
    position: absolute;
    z-index: 15;
    top: 10px;
    left: 10px;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 0.65rem;
    max-width: min(280px, calc(100% - 20px));
    pointer-events: none;
}

.pca-scatter-hud * {
    pointer-events: auto;
}

.pca-hud-reset {
    font-family: var(--font-ui);
    font-size: 0.78rem;
    font-weight: 600;
    padding: 0.4rem 0.75rem;
    border-radius: 8px;
    border: 1px solid rgba(255, 255, 255, 0.18);
    background: rgba(10, 12, 20, 0.88);
    color: rgba(255, 255, 255, 0.88);
    cursor: pointer;
    backdrop-filter: blur(8px);
    transition: background 0.15s ease, border-color 0.15s ease;
}

.pca-hud-reset:hover {
    background: rgba(28, 32, 48, 0.95);
    border-color: rgba(255, 255, 255, 0.28);
}

.pca-hud-filters {
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
    padding: 0.5rem 0.65rem;
    border-radius: 8px;
    border: 1px solid rgba(255, 255, 255, 0.12);
    background: rgba(8, 10, 16, 0.82);
    backdrop-filter: blur(8px);
}

.pca-hud-filters-title {
    font-family: var(--font-ui);
    font-size: 0.68rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: rgba(255, 255, 255, 0.45);
    margin-bottom: 0.15rem;
}

.pca-hud-filter-row {
    display: flex;
    align-items: center;
    gap: 0.45rem;
    cursor: pointer;
    font-family: var(--font-ui);
    font-size: 0.78rem;
    color: rgba(255, 255, 255, 0.82);
}

.pca-hud-filter-row input {
    width: 14px;
    height: 14px;
    accent-color: var(--accent-primary, #8b7ec8);
    cursor: pointer;
}

.pca-hud-filter-text {
    line-height: 1.3;
}

.pca-scatter-canvas canvas {
    display: block;
    width: 100%;
    height: auto;
}

.pca-scatter-canvas--loading::before {
    content: 'Loading…';
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-ui);
    font-size: 0.95rem;
    color: rgba(255, 255, 255, 0.45);
    z-index: 1;
    pointer-events: none;
}

.pca-scatter-canvas--loading::after {
    content: '';
    position: absolute;
    width: 28px;
    height: 28px;
    top: 50%;
    left: 50%;
    margin: 24px 0 0 -14px;
    border: 2px solid rgba(255, 255, 255, 0.12);
    border-top-color: rgba(255, 255, 255, 0.45);
    border-radius: 50%;
    animation: pca-spin 0.85s linear infinite;
    z-index: 1;
    pointer-events: none;
}

.pca-scatter-canvas:not(.pca-scatter-canvas--loading)::before,
.pca-scatter-canvas:not(.pca-scatter-canvas--loading)::after {
    display: none;
}

@keyframes pca-spin {
    to {
        transform: rotate(360deg);
    }
}

.pca-scatter-canvas--error {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    font-family: var(--font-ui);
    font-size: 0.95rem;
    color: rgba(255, 200, 200, 0.75);
    text-align: center;
}

.pca-scatter-footer {
    width: 68%;
    max-width: 760px;
    margin-top: 0.9rem;
    margin-left: auto;
    margin-right: auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.85rem;
    text-align: center;
}

.pca-scatter-legend {
    font-family: var(--font-ui);
    font-size: 0.88rem;
    color: rgba(255, 255, 255, 0.78);
    line-height: 1.6;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 0.65rem 1.35rem;
}

.pca-legend-row {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    margin-bottom: 0;
}

.pca-legend-swatch {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    flex-shrink: 0;
    border: 1px solid rgba(255, 255, 255, 0.2);
    box-shadow: 0 0 8px rgba(0, 0, 0, 0.35);
}

.pca-legend-label {
    color: rgba(255, 255, 255, 0.72);
}

.pca-scatter-hint {
    margin: 0;
    max-width: 52rem;
    font-family: var(--font-ui);
    font-size: 0.8rem;
    color: rgba(255, 255, 255, 0.42);
    line-height: 1.6;
}

.pca-scatter-hint-sub {
    display: block;
    margin-top: 0.45rem;
    font-size: 0.75rem;
    color: rgba(255, 255, 255, 0.34);
}

.pca-point-tooltip {
    position: absolute;
    z-index: 20;
    left: 0;
    top: 0;
    max-width: min(420px, calc(100% - 16px));
    padding: 0.55rem 0.75rem;
    border-radius: 8px;
    pointer-events: none;
    font-family: var(--font-ui);
    font-size: 0.78rem;
    line-height: 1.45;
    color: rgba(255, 255, 255, 0.92);
    background: rgba(8, 10, 18, 0.92);
    border: 1px solid rgba(255, 255, 255, 0.14);
    box-shadow: 0 8px 28px rgba(0, 0, 0, 0.45);
    backdrop-filter: blur(8px);
}

.pca-point-tooltip-coords {
    font-variant-numeric: tabular-nums;
    letter-spacing: 0.02em;
    color: rgba(255, 255, 255, 0.88);
    margin-bottom: 0.35rem;
}

.pca-point-tooltip-src {
    font-size: 0.76rem;
    font-weight: 600;
    color: rgba(200, 210, 230, 0.85);
}

@media (max-width: 900px) {
    .pca-scatter-view-wrap,
    .pca-scatter-footer {
        width: 94%;
    }

    .pca-scatter-legend {
        flex-direction: column;
        gap: 0.45rem;
    }
}

/* Architecture Diagram (Old - can be removed if not needed) */
.architecture-diagram {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.arch-item {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    text-align: center;
    min-width: 200px;
    transition: transform 0.3s ease, border-color 0.3s ease;
}

.arch-item:hover {
    transform: translateY(-5px);
    border-color: var(--accent-primary);
}

.arch-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.arch-item h3 {
    font-size: 1.3rem;
    margin-bottom: 0.5rem;
}

.arch-item p {
    font-size: 1rem;
    color: var(--text-secondary);
}

.arch-arrow {
    font-size: 2rem;
    background: linear-gradient(90deg, #2563eb, #dc2626);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.arch-feedback {
    display: flex;
    justify-content: center;
    gap: 2rem;
    flex-wrap: wrap;
}

.feedback-item {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.5rem;
    max-width: 330px;
}

.feedback-label {
    display: block;
    font-weight: 600;
    color: var(--accent-primary);
    margin-bottom: 0.5rem;
}

.feedback-item p {
    font-size: var(--font-body-size);
    color: var(--text-secondary);
}

/* Methodology Content */
.methodology-content {
    display: flex;
    flex-direction: column;
    gap: 2.1rem;
    margin-top: 0.9rem;
}

.method-text {
    display: flex;
    flex-direction: column;
    justify-content: center;
    max-width: var(--body-copy-width);
    width: 100%;
    margin: 0 auto;
}

.method-text p {
    font-size: var(--font-body-size);
    color: var(--text-secondary);
    line-height: 1.78;
    margin-bottom: var(--body-paragraph-gap);
    text-align: justify;
    text-justify: inter-word;
    hyphens: auto;
}

.method-text p::first-letter {
    font-size: 1.1em;
    font-weight: 600;
}

.method-video {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    max-width: 1320px;
    width: 100%;
    margin: 0 auto;
}

.method-video-wrapper {
    aspect-ratio: 16/4.5;
    background: var(--bg-card);
    border-radius: 16px;
    overflow: hidden;
    border: 2px solid var(--border-color);
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4);
    width: 100%;
    position: relative;
}

.method-video-element {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.method-video-note {
    margin: 1rem auto 0;
    max-width: var(--body-copy-width);
}

.method-video-note.solver-compare-note {
    font-size: 1rem;
    line-height: 1.68;
}

/* Methodology Section */
.method-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 4rem;
}

.method-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    transition: transform 0.3s ease;
}

.method-card:hover {
    transform: translateY(-5px);
}

.method-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
}

.method-number {
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--accent-primary);
    padding: 0.25rem 0.5rem;
    border: 1px solid var(--accent-primary);
    border-radius: 4px;
}

.method-card h4 {
    font-size: 1.3rem;
}

.method-card p {
    color: var(--text-secondary);
    font-size: var(--font-body-size);
}

/* Charts */
.results-section {
    margin-top: 4rem;
}

.results-charts-row {
    display: flex;
    gap: 2rem;
    align-items: stretch;
    justify-content: center;
    flex-wrap: nowrap;
    margin-top: 0;
    margin-bottom: 0.1rem;
}

@media (max-width: 1100px) {
    .results-charts-row {
        flex-wrap: wrap;
    }
}

.results-charts-row .d3-chart-container {
    flex: 1 1 572px;
    min-width: 352px;
    /* keep both charts on the same row when possible */
    max-width: none;
    margin: 0;
}

.results-phy-chapter {
    margin-top: 1.35rem;
}

#results .results-bar-section + .section-desc {
    margin-bottom: 0.55rem;
}

#results .results-charts-row + .section-desc {
    margin-bottom: 0.75rem;
}

/* Solver comparison (naive VBD vs deformation-stable canvas) */
.solver-compare-toolbar {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
    gap: 0.75rem 1rem;
    margin-top: 1.15rem;
}

.solver-compare-reset-hint {
    font-family: var(--font-ui);
    font-size: 0.78rem;
    color: rgba(255, 255, 255, 0.38);
    letter-spacing: 0.02em;
}

body.theme-light .solver-compare-reset-hint {
    color: rgba(110, 88, 60, 0.46);
}

.solver-compare-reset {
    font-family: var(--font-ui);
    font-size: 0.88rem;
    font-weight: 600;
    padding: 0.5rem 1.35rem;
    border-radius: 999px;
    border: 1px solid rgba(255, 255, 255, 0.16);
    background: rgba(14, 16, 26, 0.92);
    color: rgba(255, 255, 255, 0.88);
    cursor: pointer;
    letter-spacing: 0.03em;
    transition: background 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}

.solver-compare-reset:hover {
    background: rgba(28, 32, 48, 0.98);
    border-color: rgba(120, 200, 190, 0.35);
    color: #fff;
}

body.theme-light .solver-compare-reset {
    border-color: rgba(110, 88, 60, 0.16);
    background: rgba(245, 237, 223, 0.94);
    color: rgba(53, 40, 28, 0.88);
    box-shadow: 0 6px 18px rgba(94, 76, 56, 0.06);
}

body.theme-light .solver-compare-reset:hover {
    background: rgba(239, 229, 213, 0.98);
    border-color: rgba(96, 160, 142, 0.3);
    color: rgba(53, 40, 28, 0.96);
}

.solver-compare-drag {
    font-family: var(--font-ui);
    font-size: 0.88rem;
    font-weight: 600;
    padding: 0.5rem 1.35rem;
    border-radius: 999px;
    border: 1px solid rgba(255, 255, 255, 0.16);
    background: rgba(14, 16, 26, 0.92);
    color: rgba(255, 255, 255, 0.88);
    cursor: pointer;
    letter-spacing: 0.03em;
    transition: background 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}

@keyframes solverDragPulse {
    0%, 100% {
        border-color: rgba(255, 255, 255, 0.16);
        box-shadow: 0 0 0 0 rgba(120, 210, 255, 0);
        transform: translateY(0);
    }
    50% {
        border-color: rgba(120, 210, 255, 0.55);
        box-shadow: 0 0 0 8px rgba(120, 210, 255, 0.08);
        transform: translateY(-1px);
    }
}

.solver-compare-drag:not(.is-active) {
    animation: solverDragPulse 1.8s ease-in-out infinite;
}

.solver-compare-drag:hover {
    background: rgba(28, 32, 48, 0.98);
    border-color: rgba(130, 200, 255, 0.35);
    color: #fff;
}

body.theme-light .solver-compare-drag {
    border-color: rgba(110, 88, 60, 0.16);
    background: rgba(245, 237, 223, 0.94);
    color: rgba(53, 40, 28, 0.88);
    box-shadow: 0 6px 18px rgba(94, 76, 56, 0.06);
}

body.theme-light .solver-compare-drag:hover {
    background: rgba(239, 229, 213, 0.98);
    border-color: rgba(109, 145, 200, 0.28);
    color: rgba(53, 40, 28, 0.96);
}

.solver-compare-drag.is-active {
    animation: none;
    border-color: rgba(120, 210, 255, 0.55);
    background: rgba(18, 32, 48, 0.95);
    color: rgba(200, 240, 255, 0.98);
}

body.theme-light .solver-compare-drag.is-active {
    border-color: rgba(109, 145, 200, 0.34);
    background: rgba(222, 232, 244, 0.95);
    color: rgba(42, 58, 82, 0.96);
    box-shadow:
        0 8px 20px rgba(109, 145, 200, 0.12),
        0 0 0 1px rgba(109, 145, 200, 0.08) inset;
}

.solver-compare-drag:focus-visible {
    outline: 2px solid rgba(120, 210, 255, 0.65);
    outline-offset: 2px;
}

.solver-compare-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.75rem;
    margin-top: 1.6rem;
    margin-bottom: 2.4rem;
    align-items: stretch;
}

@media (max-width: 980px) {
    .solver-compare-grid {
        grid-template-columns: 1fr;
    }
}

.solver-compare-card {
    margin: 0;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    padding: 1.25rem 1.25rem 1.35rem;
    border-radius: 16px;
    background: linear-gradient(165deg, rgba(14, 16, 26, 0.95) 0%, rgba(8, 10, 18, 0.98) 100%);
    border: 1px solid rgba(255, 255, 255, 0.08);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.35);
}

.solver-compare-card--stable {
    border-color: rgba(100, 220, 200, 0.18);
    box-shadow:
        0 12px 40px rgba(0, 0, 0, 0.35),
        0 0 0 1px rgba(80, 200, 185, 0.06) inset;
}

body.theme-light .solver-compare-card {
    background: linear-gradient(165deg, rgba(249, 241, 229, 0.98) 0%, rgba(241, 232, 217, 0.98) 100%);
    border-color: rgba(110, 88, 60, 0.1);
    box-shadow: 0 14px 36px rgba(94, 76, 56, 0.1);
}

body.theme-light .solver-compare-card--stable {
    border-color: rgba(96, 160, 142, 0.22);
    box-shadow:
        0 14px 36px rgba(94, 76, 56, 0.1),
        0 0 0 1px rgba(96, 160, 142, 0.08) inset;
}

.solver-compare-label {
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
    font-family: var(--font-ui);
}

.solver-compare-label-title {
    font-size: 1.05rem;
    font-weight: 700;
    letter-spacing: 0.03em;
    color: rgba(255, 255, 255, 0.92);
}

.solver-compare-label-tag {
    font-size: 0.72rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: rgba(255, 255, 255, 0.38);
}

.solver-compare-label-tag--accent {
    color: rgba(120, 230, 210, 0.85);
}

body.theme-light .solver-compare-label-title {
    color: rgba(53, 40, 28, 0.92);
}

body.theme-light .solver-compare-label-tag {
    color: rgba(110, 88, 60, 0.48);
}

body.theme-light .solver-compare-label-tag--accent {
    color: rgba(78, 142, 126, 0.9);
}

.solver-compare-canvas-wrap {
    position: relative;
    width: 100%;
    min-height: 340px;
    border-radius: 12px;
    overflow: hidden;
    border: 1px solid rgba(255, 255, 255, 0.06);
    background: radial-gradient(ellipse 120% 80% at 50% 0%, rgba(30, 40, 70, 0.35) 0%, transparent 55%),
        #060810;
}

body.theme-light .solver-compare-canvas-wrap {
    border-color: rgba(110, 88, 60, 0.08);
    background:
        radial-gradient(ellipse 120% 80% at 50% 0%, rgba(192, 176, 151, 0.28) 0%, transparent 55%),
        linear-gradient(180deg, rgba(244, 236, 224, 0.98) 0%, rgba(236, 226, 211, 0.98) 100%);
}

body.theme-light .solver-compare-canvas-wrap--stable {
    border-color: rgba(96, 160, 142, 0.16);
    background:
        radial-gradient(ellipse 120% 80% at 50% 0%, rgba(176, 202, 191, 0.24) 0%, transparent 55%),
        linear-gradient(180deg, rgba(242, 235, 223, 0.98) 0%, rgba(233, 224, 208, 0.98) 100%);
}

.solver-compare-canvas-wrap canvas {
    display: block;
    width: 100%;
    height: 100%;
    min-height: 340px;
}

.solver-compare-note {
    margin: 0;
    font-family: var(--font-ui);
    font-size: 0.92rem;
    line-height: 1.62;
    color: rgba(255, 255, 255, 0.48);
    text-align: left;
    text-justify: auto;
    letter-spacing: 0.01em;
}

.solver-note-accent {
    color: rgba(190, 235, 110, 0.92);
}

/* Results: stacked video reels (zip_1, zip, novel_solver) */
.results-videos-gallery--second {
    margin-top: 1.75rem;
}

.results-videos-gallery--novel {
    margin-top: 1.75rem;
}

.results-videos-gallery--novel .solver-card {
    flex: 0 0 auto;
    width: fit-content;
}

.results-videos-gallery--novel .solver-vid-wrap {
    height: calc(462px * 9 / 16);
    width: auto;
    max-width: none;
    background: rgba(0, 0, 0, 0.55);
}

.results-videos-gallery--novel .solver-vid-wrap video {
    object-fit: contain;
    background: #000;
}

.results-bar-section {
    margin-top: 2.5rem;
    margin-bottom: 2rem;
}

.results-bar-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0rem;
    margin-bottom: 0.5rem;
}

.results-bar-header .subsection-title {
    margin-bottom: 0;
}

.results-bar-panels {
    display: flex;
    gap: 1.25rem;
    margin-top: 1rem;
    align-items: stretch;
    flex-wrap: nowrap;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

.results-bar-panel--small {
    /* fewer bars → narrower panel */
    flex: 0 0 150px;
    max-width: 150px;
}

.results-bar-panel--large {
    flex: 1 1 462px;
    min-width: 352px;
}

.results-bar-panel-title {
    margin: 0 0 0.6rem;
    font-family: var(--font-ui);
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: 0.02em;
}

.results-bar-legend {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem 1.25rem;
    margin-top: 0.85rem;
    color: rgba(255, 255, 255, 0.72);
    font-family: var(--font-ui);
    font-size: 0.9rem;
}

.bar-legend-item {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.bar-legend-swatch {
    width: 12px;
    height: 12px;
    border-radius: 3px;
    display: inline-block;
}

/* Swap palette mapping:
   Real  ← Gen color
   Tele  ← Real color
   Gen   ← Tele color */
.swatch-real { background: rgba(191, 191, 191, 0.95); }
.swatch-tele { background: rgba(202, 172, 197, 0.95); }
.swatch-gen  { background: rgba(128, 109, 155, 0.95); }

.results-bar-chart {
    margin-top: 0;
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 14px;
    padding: 1.1rem 1.1rem 0.9rem;
    position: relative;
    overflow: hidden;
}

.bar-groups {
    display: grid;
    grid-template-columns: repeat(5, 99px);
    gap: 0.35rem;
    align-items: end;
    justify-content: center;
}

/* Small panel only has 1 task-group: keep it narrow & centered */
.results-bar-panel--small .bar-groups {
    grid-template-columns: 99px;
    width: fit-content;
    margin: 0 auto;
}

@media (max-width: 1100px) {
    .bar-groups { grid-template-columns: repeat(3, 90px); }
}
@media (max-width: 700px) {
    .bar-groups { grid-template-columns: repeat(2, 90px); }
}

.bar-group {
    display: grid;
    grid-template-rows: 220px auto;
    gap: 0.35rem;
}

.bar-stack {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    /* fixed, tighter spacing within each task */
    gap: 5px;
    align-items: end;
    height: 220px;
}

.results-bar-panel--small .bar-stack {
    /* 2 bars only: size to bar width, center them */
    grid-template-columns: repeat(2, 22px) !important;
    justify-content: center;
    gap: 3px;
}

.results-bar-panel--small .results-bar-chart .bar {
    max-width: 20px;
}

.results-bar-chart .bar {
    /* start from a visible baseline */
    height: var(--bar-base, 6px);
    border-radius: 10px 10px 6px 6px;
    transition: height 2000ms cubic-bezier(.2,.9,.2,1);
    position: relative;
    will-change: height;
    /* thinner bars */
    max-width: 20px;
    margin: 0 auto;
}

.results-bar-chart .bar.real { background: rgba(191, 191, 191, 0.85); }
.results-bar-chart .bar.tele { background: rgba(202, 172, 197, 0.85); }
.results-bar-chart .bar.gen  { background: rgba(128, 109, 155, 0.85); }

.results-bar-chart.is-animated .bar {
    height: var(--bar-h);
}

.bar-label {
    text-align: center;
    font-family: var(--font-ui);
    font-size: 0.92rem;
    font-weight: 600;
    color: rgba(255, 255, 255, 0.82);
}

.results-bar-tooltip {
    position: fixed;
    z-index: 9999;
    left: 0;
    top: 0;
    opacity: 0;
    /* opacity only — avoid translateY here fighting JS top/left */
    transition: opacity 120ms ease;
    padding: 10px 12px;
    border-radius: 12px;
    background: var(--chart-tooltip-bg);
    border: 1px solid var(--chart-tooltip-border);
    backdrop-filter: blur(8px);
    pointer-events: none;
    color: var(--chart-tooltip-text);
    font-family: var(--font-ui);
    font-size: 0.9rem;
    min-width: 140px;
}

.results-bar-tooltip.is-visible {
    opacity: 1;
}

.tooltip-title {
    font-weight: 700;
    margin-bottom: 4px;
}

.tooltip-row {
    display: flex;
    justify-content: space-between;
    gap: 10px;
    color: var(--chart-tooltip-text);
}
.phy-video-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(242px, 1fr));
    gap: 1.25rem;
    margin-top: 1.25rem;
}

@media (max-width: 900px) {
    .phy-video-grid {
        grid-template-columns: repeat(2, minmax(242px, 1fr));
    }
}

@media (max-width: 600px) {
    .phy-video-grid {
        grid-template-columns: 1fr;
    }
}

.phy-video-card {
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 14px;
    overflow: hidden;
    margin: 0;
}

.phy-video {
    width: 100%;
    height: auto;
    display: block;
    aspect-ratio: 16 / 9;
    object-fit: cover;
    background: rgba(0, 0, 0, 0.25);
}

.phy-video-card figcaption {
    padding: 0.75rem 0.9rem;
    font-family: var(--font-ui);
    font-size: 0.95rem;
    color: rgba(255, 255, 255, 0.85);
    border-top: 1px solid rgba(255, 255, 255, 0.06);
}

.chart-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.chart-item {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.5rem;
}

.chart-item h4 {
    font-size: 1.2rem;
    margin-bottom: 1rem;
    text-align: center;
}

.chart-placeholder {
    background: rgba(0, 0, 0, 0.3);
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 1rem;
}

.bar-chart {
    display: flex;
    align-items: flex-end;
    justify-content: center;
    gap: 1rem;
    height: 150px;
}

.bar {
    width: 60px;
    background: linear-gradient(180deg, #2563eb 0%, #dc2626 100%);
    border-radius: 4px 4px 0 0;
    position: relative;
    opacity: 0.6;
    transition: opacity 0.3s ease;
}

.bar.highlight {
    opacity: 1;
    box-shadow: 0 0 20px rgba(37, 99, 235, 0.5);
}

.bar span {
    position: absolute;
    bottom: -25px;
    left: 50%;
    transform: translateX(-50%);
    font-size: 0.7rem;
    color: var(--text-secondary);
    white-space: nowrap;
}

.chart-desc {
    font-size: 1rem;
    color: var(--text-secondary);
    text-align: center;
    line-height: 1.65;
}

/* Model Section */
.model-chart {
    margin-top: 2rem;
}

.chart-placeholder.large {
    padding: 2rem;
}

.comparison-chart {
    display: flex;
    align-items: flex-end;
    justify-content: center;
    gap: 3rem;
    height: 200px;
}

.comp-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
}

.comp-bar {
    width: 80px;
    background: linear-gradient(180deg, #2563eb 0%, #dc2626 100%);
    border-radius: 4px 4px 0 0;
    opacity: 0.6;
    transition: opacity 0.3s ease;
}

.comp-item.highlight .comp-bar {
    opacity: 1;
    box-shadow: 0 0 30px rgba(37, 99, 235, 0.5);
}

.comp-item span {
    font-size: 1rem;
    color: var(--text-secondary);
}

/* Stage Advantage */
.stage-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

.stage-visual {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
}

.trajectory-chart {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.traj-line {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.traj-line.highlight .traj-label {
    color: #2563eb;
}

.traj-label {
    font-size: 1rem;
    color: var(--text-secondary);
    min-width: 150px;
}

.traj-segments {
    display: flex;
    gap: 0.25rem;
    flex: 1;
}

.segment {
    flex: 1;
    height: 8px;
    border-radius: 4px;
}

.segment.green {
    background: #2563eb;
}

.segment.red {
    background: #dc2626;
}

.visual-desc {
    font-size: 1rem;
    color: var(--text-secondary);
    text-align: center;
    margin-top: 1.5rem;
}

.stage-metrics {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.metric-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.metric-label {
    font-size: 1rem;
    color: var(--text-secondary);
}

.metric-value {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--success);
}

.metric-card p {
    font-size: 1rem;
    color: var(--text-secondary);
}

/* Highlight Section */
.highlight-section {
    background-image: var(--paper-texture), linear-gradient(135deg, rgba(37, 99, 235, 0.85) 0%, rgba(220, 38, 38, 0.85) 100%);
    text-align: center;
}

.quote {
    border: none;
    padding: 0;
    margin-bottom: 1.25rem;
}

.quote p {
    font-family: 'EB Garamond', Georgia, serif;
    font-size: 1.9rem;
    font-style: italic;
    font-weight: 400;
    margin-bottom: 0.4rem;
    text-align: center;
}

.quote cite {
    font-size: 0.875rem;
    font-family: var(--font-ui);
    opacity: 0.8;
    letter-spacing: 0.06em;
}

.highlight-text {
    font-size: var(--font-body-size);
    opacity: 0.9;
    text-align: center;
    text-justify: auto;
    max-width: 920px;
    margin: 0 auto var(--body-paragraph-gap);
}

/* Citation */
.citation-box {
    position: relative;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    max-width: 836px;
    margin: 0 auto;
    padding: 2rem;
    overflow: hidden;
}

.citation-scroll {
    overflow-x: auto;
    overflow-y: hidden;
    padding-top: 0.25rem;
}

.citation-box pre {
    margin: 0;
}

.citation-box code {
    font-family: 'Fira Code', 'Courier New', monospace;
    font-size: 1.0625rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

.citation-copy-btn {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: rgba(255, 255, 255, 0.06);
    border: 1px solid rgba(255, 255, 255, 0.12);
    border-radius: 6px;
    color: rgba(255, 255, 255, 0.45);
    cursor: pointer;
    padding: 0.4rem;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    transition: color 0.15s ease, background 0.15s ease, border-color 0.15s ease;
    line-height: 0;
}

.citation-copy-btn svg {
    width: 15px;
    height: 15px;
}

.citation-copy-btn:hover {
    color: rgba(255, 255, 255, 0.85);
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.25);
}

.citation-copy-btn.copied {
    color: #4ade80;
    border-color: rgba(74, 222, 128, 0.35);
    background: rgba(74, 222, 128, 0.08);
}

/* Newsletter */
.newsletter {
    text-align: center;
}

.newsletter .container {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.newsletter .section-desc,
.newsletter .form-note {
    text-align: center;
    text-justify: auto;
}

.newsletter-form {
    display: flex;
    gap: 1rem;
    max-width: 550px;
    width: min(550px, 100%);
    margin: 2rem auto 1rem;
}

.email-input {
    flex: 1;
    padding: 1rem 1.5rem;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-primary);
    font-size: 1rem;
    outline: none;
    transition: border-color 0.3s ease;
}

.email-input:focus {
    border-color: var(--accent-primary);
}

.email-input::placeholder {
    color: var(--text-secondary);
}

.submit-btn {
    padding: 1rem 2rem;
    background: linear-gradient(135deg, #2563eb 0%, #dc2626 100%);
    border: none;
    border-radius: 8px;
    color: white;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.submit-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 30px rgba(37, 99, 235, 0.4);
}

.form-note {
    font-size: 1.0625rem;
    color: var(--text-secondary);
}

/* Footer */
.footer {
    background-color: var(--bg-primary);
    background-image: var(--paper-texture);
    border-top: 1px solid var(--border-color);
    padding: 2rem;
    text-align: center;
}

.footer p {
    color: var(--text-secondary);
    font-size: 1.0625rem;
}

/* Responsive */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .hero-meta {
        max-width: 100%;
    }

    .meta-item {
        flex-direction: column;
        gap: 0.15rem;
    }

    .meta-label {
        min-width: unset;
    }
    
    .methodology-content {
        grid-template-columns: 1fr;
    }
    
    .solver-card {
        flex: 0 0 72vw;
    }
    
    .architecture-diagram {
        flex-direction: column;
    }
    
    .arch-arrow {
        transform: rotate(90deg);
    }
    
    .stage-content {
        grid-template-columns: 1fr;
    }
    
    .newsletter-form {
        flex-direction: column;
    }
    
    .comparison-chart {
        gap: 1.5rem;
    }
    
    .comp-bar {
        width: 50px;
    }
}

/* Animations */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.section {
    animation: fadeIn 0.6s ease-out;
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
    background: var(--bg-card);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent-primary);
}

/* ── Trajectory synthesis (dual canvas, “wave” backdrop) ── */
.trajectory-section {
    position: relative;
    overflow: hidden;
    padding-top: var(--section-space-y);
    padding-bottom: var(--section-space-y);
    background-color: var(--bg-secondary);
    background-image:
        var(--paper-texture),
        radial-gradient(ellipse 110% 80% at 50% 108%, rgba(32, 38, 62, 0.36), transparent 56%),
        radial-gradient(ellipse 86% 52% at 18% 98%, rgba(28, 34, 52, 0.28), transparent 53%),
        radial-gradient(ellipse 90% 56% at 82% 98%, rgba(30, 36, 54, 0.26), transparent 54%),
        linear-gradient(185deg, #06070c 0%, #0e1018 42%, #0c0d12 72%, var(--bg-secondary) 100%);
}

.trajectory-section::before {
    content: '';
    position: absolute;
    inset: 0;
    pointer-events: none;
    opacity: 0.24;
    background: repeating-linear-gradient(
        102deg,
        transparent 0,
        transparent 36px,
        rgba(255, 255, 255, 0.028) 36px,
        rgba(255, 255, 255, 0.028) 37px
    );
    mask-image: linear-gradient(to bottom, rgba(0, 0, 0, 0.95) 0%, rgba(0, 0, 0, 0.6) 62%, rgba(0, 0, 0, 0) 100%);
    animation: trajectory-wave-drift 24s linear infinite;
}

.trajectory-section::after {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    bottom: 0;
    height: 36%;
    pointer-events: none;
    opacity: 0.34;
    background:
        linear-gradient(to bottom, rgba(10, 10, 10, 0) 0%, rgba(10, 10, 10, 0.92) 100%),
        radial-gradient(ellipse 52% 34% at 12% 100%, rgba(42, 48, 72, 0.16), transparent 72%),
        radial-gradient(ellipse 46% 30% at 48% 100%, rgba(38, 44, 68, 0.14), transparent 68%),
        radial-gradient(ellipse 55% 36% at 88% 100%, rgba(40, 46, 70, 0.15), transparent 70%);
    animation: trajectory-dune-breathe 16s ease-in-out infinite alternate;
}

@keyframes trajectory-wave-drift {
    to {
        transform: translateX(-28px);
    }
}

@keyframes trajectory-dune-breathe {
    from {
        transform: translateY(0);
        opacity: 0.48;
    }
    to {
        transform: translateY(-8px);
        opacity: 0.62;
    }
}

.trajectory-section .container {
    position: relative;
    z-index: 1;
}

.trajectory-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    margin-top: 2.25rem;
    margin-bottom: 0.5rem;
    align-items: stretch;
}

@media (max-width: 960px) {
    .trajectory-grid {
        grid-template-columns: 1fr;
    }
}

.trajectory-card {
    margin: 0;
    padding: 1.25rem 1.2rem 1.35rem;
    border-radius: 14px;
    border: 1px solid rgba(255, 255, 255, 0.09);
    background: rgba(4, 5, 10, 0.45);
    backdrop-filter: blur(6px);
}

.trajectory-card-title {
    font-family: var(--font-ui);
    font-size: 1rem;
    font-weight: 600;
    color: rgba(255, 255, 255, 0.88);
    margin: 0 0 0.65rem;
    letter-spacing: 0.02em;
}

.trajectory-canvas-wrap {
    width: 100%;
    border-radius: 10px;
    overflow: hidden;
    background: linear-gradient(180deg, rgba(8, 10, 18, 0.95), rgba(6, 7, 12, 0.98));
    border: 1px solid rgba(255, 255, 255, 0.06);
    min-height: 320px;
}

.trajectory-canvas-wrap canvas {
    display: block;
    width: 100%;
    height: auto;
}

.trajectory-card-note {
    margin: 0.85rem 0 0;
    font-family: var(--font-ui);
    font-size: 0.92rem;
    line-height: 1.62;
    color: rgba(255, 255, 255, 0.48);
    text-align: left;
    text-justify: auto;
    letter-spacing: 0.01em;
}

/* Lock long-form narrative paragraphs to one consistent editorial style.
   Scoped by section and placed late so local layout rules won't override typography. */
#introduction .arch-description,
#methodology .method-text p,
#solver-compare .section-desc,
#trajectory-gen .section-desc,
#pca-viz .section-desc,
#results .section-desc {
    font-family: var(--font-body);
    font-weight: 400;
    font-optical-sizing: auto;
    font-feature-settings: 'kern' 1, 'liga' 1;
    text-rendering: optimizeLegibility;
    font-size: var(--font-body-size);
    color: var(--text-secondary);
    line-height: 1.78;
    max-width: var(--body-copy-width);
    text-align: justify;
    text-justify: inter-word;
    hyphens: auto;
    margin-bottom: var(--body-paragraph-gap);
}

#introduction .arch-description::first-letter,
#methodology .method-text p::first-letter,
#solver-compare .section-desc::first-letter,
#trajectory-gen .section-desc::first-letter,
#pca-viz .section-desc::first-letter,
#results .section-desc::first-letter {
    font-size: 1.1em;
    font-weight: 600;
}

/* Scroll Progress Bar */
.scroll-progress {
    position: fixed;
    top: 0;
    left: 0;
    height: 6px;
    background: linear-gradient(90deg, #2563eb, #dc2626);
    z-index: 9999;
    transition: width 0.1s ease;
    box-shadow: 0 0 10px rgba(37, 99, 235, 0.5);
}

/* Results Section SVG */
.svg-container {
    max-width: 1210px;
    width: 100%;
    margin: 3rem auto 0;
    display: flex;
    justify-content: center;
    align-items: center;
}

.results-svg {
    width: 100%;
    height: auto;
    max-width: 990px;
    border-radius: 8px;
    background: #ffffff;
    padding: 1rem;
}

/* D3 Chart Container */
.d3-chart-container {
    max-width: 836px;
    width: 100%;
    margin: 3rem auto 0;
    background: transparent;
    border-radius: 8px;
    padding: 2rem;
    min-height: 550px;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: visible;
}

.results-chart {
    width: 100%;
    height: 100%;
    background: transparent;
    display: block;
}

.results-chart .grid line {
    stroke: var(--chart-grid-color) !important;
    stroke-dasharray: 3, 3;
    stroke-width: 0.5;
}

.results-chart .grid path {
    display: none;
}

.results-chart .x.axis,
.results-chart .y.axis {
    stroke: var(--chart-axis-color);
    stroke-width: 1;
}

.results-chart .x.axis line,
.results-chart .y.axis line {
    stroke: var(--chart-axis-color) !important;
    stroke-width: 1;
}

.results-chart .x.axis path.domain,
.results-chart .y.axis path.domain {
    stroke: var(--chart-axis-color) !important;
    stroke-width: 1;
    fill: none;
}

.results-chart .x.axis text,
.results-chart .y.axis text {
    fill: var(--chart-axis-text-color) !important;
    font-size: 12px;
    font-family: var(--font-ui);
    font-weight: 400;
}

.axis-label {
    fill: var(--chart-label-color) !important;
    font-family: var(--font-ui);
    font-size: 17px;
    font-weight: 400;
}

.results-chart .fit-line {
    stroke-linecap: round;
    stroke-linejoin: round;
    stroke-opacity: 1 !important;
}

.results-chart .error-band {
    stroke: none;
    /* More visible; JS may also set opacity */
    fill-opacity: 0.14 !important;
}

.results-chart .legend text {
    font-family: var(--font-ui);
    fill: var(--chart-label-color) !important;
}

.results-chart .legend circle,
.results-chart .legend rect,
.results-chart .legend polygon {
    stroke: var(--chart-marker-stroke) !important;
    stroke-width: 2 !important;
    fill-opacity: 1 !important;
}

.results-chart .data-point-marker {
    pointer-events: all;
    opacity: 1 !important;
}

.results-chart .data-point-marker circle {
    fill-opacity: 1 !important;
    r: 8 !important;
}

.results-chart .data-point-marker rect {
    fill-opacity: 1 !important;
}

.results-chart .data-point-marker polygon {
    fill-opacity: 1 !important;
}

.results-chart line {
    stroke-opacity: 0.9 !important;
    pointer-events: none;
}

/* Chart Tooltip */
.chart-tooltip {
    position: fixed;
    left: 0;
    top: 0;
    margin: 0;
    /* position set via transform in JS (avoids left/top + scroll quirks) */
    background: var(--chart-tooltip-bg);
    color: var(--chart-tooltip-text);
    padding: 12px 16px;
    border-radius: 8px;
    font-family: var(--font-ui);
    font-size: 13px;
    pointer-events: none;
    border: 1px solid var(--chart-tooltip-border);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    z-index: 10000;
    min-width: 200px;
}

/* Live Demo Section */
.demo-container {
    max-width: 1320px;
    width: 100%;
    margin: 2rem auto 0;
    background: var(--bg-card);
    border-radius: 16px;
    overflow: hidden;
    border: 2px solid var(--border-color);
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4);
    aspect-ratio: 16/9;
    position: relative;
}

.demo-iframe {
    width: 100%;
    height: 100%;
    border: none;
    background: var(--bg-card);
}

.demo-controls-info {
    display: flex;
    justify-content: center;
    gap: 4rem;
    margin-top: 2rem;
    flex-wrap: wrap;
}

.control-group {
    text-align: center;
}

.control-group h4 {
    font-size: 1.1rem;
    color: var(--text-primary);
    margin-bottom: 0.75rem;
    font-weight: 600;
}

.control-group p {
    font-size: 1.0625rem;
    color: var(--text-secondary);
    line-height: 1.6;
    text-align: center;
    text-justify: auto;
}

.form-note,
.highlight-text {
    text-justify: auto;
}

.pca-scatter-view-wrap,
.pca-scatter-footer {
    width: min(100%, var(--media-copy-width));
    max-width: none;
}

@media (max-width: 768px) {
    .section {
        padding: 2.35rem 1.35rem;
    }

    .section-desc,
    .arch-description,
    .method-text,
    .method-video-note,
    .pca-scatter-view-wrap,
    .pca-scatter-footer {
        max-width: 100%;
        width: 100%;
    }
}

.control-group kbd {
    display: inline-block;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    padding: 0.2rem 0.5rem;
    font-family: 'Courier New', monospace;
    font-size: 0.85rem;
    color: var(--accent-primary);
    margin: 0 0.1rem;
}

.tooltip-content {
    line-height: 1.6;
}

.tooltip-header {
    font-weight: 600;
    font-size: 14px;
    margin-bottom: 6px;
    padding-bottom: 6px;
    border-bottom: 1px solid var(--chart-tooltip-border);
}

.tooltip-row {
    display: flex;
    justify-content: space-between;
    gap: 12px;
}

.tooltip-label {
    color: var(--chart-tooltip-muted);
}

.tooltip-value {
    font-weight: 500;
    color: var(--chart-tooltip-text);
}

.tooltip-equation {
    margin-top: 8px;
    padding-top: 8px;
    border-top: 1px solid var(--chart-tooltip-border);
}

.tooltip-math {
    font-family: 'Courier New', monospace;
    font-size: 12px;
    color: #90EE90;
    display: block;
    line-height: 1.8;
}