Improve mobile layout on Load Balancers page (topic 05)

[sridhar-3009]

What

The company badges and cards grid on topics/05-load-balancers.html overflow or stack awkwardly on screens below 480px.

Steps to reproduce

1. Open the live site: https://sridhar-3009.github.io/System-Design-Course/topics/05-load-balancers.html
2. Set browser width to 375px (iPhone viewport)
3. Scroll to the "Real-World Usage" section

Expected

Company badges wrap cleanly. Cards stack to single column.

Where to fix

css/style.css — add breakpoint rules inside the existing @media (max-width: 600px) block.

Difficulty: Easy — CSS only.