- add responsive design with mobile breakpoints

- implement mobile keyboard support with hidden input field
- move `@keyframes blink` to fix missing semicolon syntax error
- optimize UI for small screens
  - reduce font sizes
  - adjust padding and spacing
  - make buttons more compact
  - add horizontal scrolling for tab buttons
- improve mobile UX with tap-to-focus keyboard functionality
- restructure CSS with proper media queries
- simplify HTML structure for better performance

Author: TobiasMue91