Your design changes based on platform constraints.
Questions to ask:
- Desktop only, mobile only, or both?
- Which browsers must be supported?
- Any legacy browser requirements (IE)?
- Touch interactions needed?
Why it matters:
- Mobile needs touch-friendly targets (px minimum)
- Legacy browsers limit CSS/JS features
- Responsive design adds complexity
Interview tip: If not specified, assume modern browsers and responsive design. State your assumption explicitly.