CSS Mistakes That Destroy Responsive Design

CSS mistakes silently break layouts, especially on mobile. These are the most common problems developers face daily.

1. Using Fixed Widths

Fixed pixel widths break responsiveness. Always use flexible units.

2. Not Using Flexbox or Grid

Modern layouts require CSS Grid and Flexbox.

3. Ignoring Mobile Testing

Most traffic is mobile — ignoring it kills UX and SEO.

4. Overusing !important

This creates unmaintainable CSS conflicts.

5. Not Optimizing Images

Large images destroy loading speed.