For web developers, the viewport—the visible area of a webpage on a device—is foundational to responsive design. But in Safari 26, it's reportedly “utterly broken,” according to a recent Bluesky post by Bramus, a respected figure in web standards advocacy. This isn't just a minor glitch; it's a regression from issues first documented in 2022, signaling a troubling decline in Apple's browser reliability on iOS devices.

Bramus's frustration is palpable: “Viewport behavior in Safari 26 is utterly broken. 🙄😭 Time to get Viewports into #Interop2026 because viewports on iOS have gotten only worse since I did the initial research in, checks notes, 2022.” He links to his GitHub repository, which details early interoperability tests revealing inconsistencies in how Safari handles dynamic viewport units (like vh and vw), essential for fluid layouts. These units often misbehave during scrolling or orientation changes, causing elements to jump or resize incorrectly—a nightmare for developers aiming for seamless mobile experiences.

Why This Regression Matters

Viewport issues aren't just cosmetic; they erode user trust and accessibility. For instance, broken viewports can distort form inputs or navigation bars on iPhones, leading to higher bounce rates. Since Bramus's 2022 research, the problem has escalated, with Safari 26 introducing new bugs that exacerbate layout shifts. This backslide undermines efforts toward a consistent web, where developers expect standards like CSS Viewport Modules to work uniformly across browsers.

The call for Interop2026—a collaborative initiative by browser vendors to prioritize compatibility—is a strategic move. Including viewports could force Apple to address these flaws, much like Interop2022 tackled areas like CSS Grid. Without it, developers face increased testing burdens and workarounds, fragmenting the ecosystem. As one expert noted, “When core specs fail in dominant browsers, it stalls innovation and wastes countless hours on patches.”

For now, Bramus's advocacy serves as a rallying cry. If Interop2026 adopts viewports, it could catalyze fixes, ensuring Safari doesn't hold back the mobile web. But until then, developers must brace for more instability in their iOS builds.

Source: Bramus on Bluesky