iPhone Air: Screen Size & CSS Viewport

The iPhone Air introduces a new viewport width to the iPhone family. At 420×912 CSS pixels it is wider than the 402px iPhone 17 and 17 Pro but narrower than the 440px Pro Max, a new size in the 400 to 440px range that your designs should accommodate.

The 5.6 mm ultra-thin chassis is the engineering headline, but for responsive design the key implication is the larger display at a new CSS width. If your breakpoints jump from a 390px rule to a 430px rule, the 420px Air falls in a gap. Components that are precisely sized for 390px or 430px may look subtly cramped or spacious on the Air. A quick media query check at 420px is worth adding to your mobile test suite.

The Always-On display means content is visible even when the screen is technically dimmed — including any persistent notifications, badges, or widgets your web app may show. Consider how your site looks at reduced brightness: low-contrast text, light backgrounds, and ghost-white overlays will be even harder to read in this state. Ensure your interface maintains legibility at reduced display luminance.