iPhone 17: Screen Size & CSS Viewport

The iPhone 17 is the first standard (non-Pro) iPhone to ship with ProMotion 120 Hz, a milestone that closes the display quality gap between Apple's base and Pro models. For web developers this has a direct implication: scroll-driven animations, CSS transitions, and canvas-based effects that previously looked smooth on Pro iPhones but "fine" on standard models will now look consistently smooth across the entire iPhone 17 line — raising the bar for animation quality at 402px width.

The 402px CSS viewport width is the same as the iPhone 16 Pro, making this a stable testing target shared across both base and pro tiers. Any media query adjustment you add for 402px will benefit the combined audience of both models.

At 2000 nits outdoor peak brightness, iPhone 17 users are highly likely to view your site in sunlight. This is the moment to check color contrast ratios — not just WCAG AA (4.5:1 for normal text) but also how your brand colors, call-to-action buttons, and background/text pairings read in direct sunlight simulation. Low-contrast design choices that look acceptable in a darkened studio are exposed on a sunny day.