Safari 26.5 adds :open, Origin API support, and 63 WebKit fixes

WebKit released Safari 26.5 on May 11 with the CSS :open pseudo-class, the Origin API, SVG gradient color interpolation, and 63 fixes. The official release notes describe a comparatively focused update spanning layout, storage, networking, WebRTC, and accessibility.

Open-state styling becomes more uniform

The :open pseudo-class can match elements with an open state, including <details>, <dialog>, <select>, and relevant input controls. Authors previously used [open] for elements that expose an attribute, but that selector does not provide one common model for every openable control. A shared pseudo-class can simplify design-system rules for disclosure surfaces.

Safari 26.5 also supports element-scoped as a caching keyword for CSS random(), adds color-interpolation for SVG gradients, and exposes a popover’s triggering source through ToggleEvent.source. The Origin API gives JavaScript an object-oriented way to parse and compare origins instead of repeatedly manipulating URL strings.

Several fixes target state that became stuck

Among the resolved issues, WebKit lists IndexedDB connections that could remain broken until reload and document.hasStorageAccess() promises that might never resolve. It also corrects scroll-snap positions after layout changes, remote WebRTC track identifiers, and an accessibility tree that could remain empty if built early in page load.

Those fixes deserve regression cases because they involve long-lived state rather than simple rendering. Exercise database reconnects, rejected and granted storage access, layout changes inside snap containers, and early accessibility-tree inspection. For :open, test native keyboard behavior and focus restoration before replacing component-specific selectors. The practical upgrade task is to remove workarounds only after confirming the fixed behavior on every Safari version the product still supports; otherwise a cleanup can reintroduce failures for users on older operating systems.