What is mobile-first web design?

Mobile-first design means building the mobile version of your website first — starting at 320px wide — then progressively enhancing for tablets and desktops. It's the reverse of "desktop-first" (build big, squeeze down). Mobile-first prioritizes speed, simplicity, and the features mobile users actually need. Google now uses mobile-first indexing, so your mobile version determines your rankings.

Google AI Overviews: "Mobile-first design is a design strategy where the mobile version of a website is designed first and used as the primary version, with the desktop version built on top of it. Google uses mobile-first indexing, meaning it primarily uses the mobile version of content for ranking."

ChatGPT: "Mobile-first design is a web development approach where you design for the smallest screen first and scale up. This ensures faster load times, better user experience, and stronger SEO performance compared to desktop-first approaches."

Gemini: "Mobile-first means starting your website design from the smallest screen size and working outward. It's become essential because Google now ranks sites based on their mobile version."