Safari 27.1 shipped on October 23, 2026, the day the iPhone Duo reached stores, and Apple’s WebKit team says websites still cannot draw behind the browser controls on the foldable’s outer display. Jen Simmons wrote on the WebKit blog that engineers are looking for a better way to let pages use that space. Until then, Safari fills the gap with the page’s background color. If a site looks boxed in on the small outer screen, that rule is the reason, and Apple has not said when it will change.
TL;DR: Safari 27.1 on the iPhone Duo moves its controls to the side of the outer display and keeps web content out from under them. Apple’s WebKit team is investigating a safer way to let sites use that space, with no date given. Safari also adds a two page PDF view and two preview APIs for folding screens, both hidden behind feature flags.
How iPhone Duo Safari treats the outer display
The outer display is wider and shorter than any other iPhone screen, and it works in portrait or landscape. Safari puts the tab bar at the bottom by default.
When the phone is closed, iOS moves the browser controls to the side of the screen. That frees vertical room for the page, which matters on a display this short. According to the WebKit post, the viewport runs from 382 to 951 CSS pixels wide and 368 to 902 tall across all of the phone’s poses.
Those numbers are a wide spread for a single phone, and web developers have to design for every point in between. That is where the side controls start to cause trouble.
Why web content stops short of the controls
In Safari 27.1, web content does not extend behind the side controls, and Safari stretches the page’s background color into that area instead. A header image or a colored banner therefore ends before the screen edge, with a flat strip beside it.
Developers can already set viewport-fit="cover" to push content to the edges. The WebKit post explains the catch: many sites do not inset all four edges correctly, so text and buttons could end up underneath the controls. A tap on a menu link that lands on a Safari button is a worse result than a plain strip of color.
So Apple is holding back, and Simmons wrote that WebKit is “investigating if there’s a better way to accomplish the same result.” On a screen this small, a flat band along one edge is easy to notice. It is still the safer default until a more foolproof option exists.
Safari 27.1 features built for a folding screen
Safari 27.1 adds a two page view for PDFs when the phone is partly folded, so each half of the screen shows one page. It is the one change in this release that an ordinary owner will see without doing anything.
The rest is for developers. The Device Posture API reports whether the screen is folded or continuous, through a CSS media query and navigator.devicePosture. The Viewport Segments API describes the display areas on each side of the fold using media queries, six environment variables, and window.viewport.segments.
Both are previews. To try them, open Settings, then Apps, Safari, Advanced, and Feature Flags, and switch them on. Sites will only respond to the fold once their authors build for it, which takes time.
What this means if you own an iPhone Duo
You do not need to change a setting. Simmons describes the release as using the same WebKit engine and web technologies as other iPhones, adding that “the ‘big news’ here is no news.” The software side of launch day is also quieter than the hardware: iOS 27.1 is an iPhone Duo only release.
If a favorite site looks off on the outer screen, the likely cause is how that page handles its edges, not a fault in your phone. The WebKit post gives no date for a change.
