Mobile-First Responsive Design (2025/2026)

Core Philosophy

Mobile-first design is the industry standard for 2025/2026. With mobile traffic consistently exceeding 60% of global web traffic and Google's mobile-first indexing, starting with mobile ensures optimal user experience and SEO performance.

The Mobile-First Mindset

<!-- CORRECT: Mobile-first (progressive enhancement) -->
<div class="text-sm md:text-base lg:text-lg">Start small, enhance upward</div>

<!-- INCORRECT: Desktop-first (graceful degradation) -->
<div class="text-sm md:text-base lg:text-lg">
  Starts large, reduces down (more code, more bugs)
</div>

Key Principle: Unprefixed utilities apply to ALL screen sizes. Breakpoint prefixes apply at that size AND ABOVE.