Release Notes for Safari Technology Preview 248 | WebKit

Release Notes for Safari Technology Preview 248

Jul 22, 2026

by Jon Davis

Safari Technology Preview Release 248 is now available for download for macOS Golden Gate and macOS Tahoe. If you already have Safari Technology Preview installed, you can update it in System Settings under General → Software Update.

This release includes WebKit changes between: 315567@main…316817@main.

Accessibility

Resolved Issues

Fixed VoiceOver on Safari unable to navigate to content revealed by disclosure widgets using hidden="until-found". (315964@main) (173228707)

Fixed stale aria-labelledby when the referenced element dynamically changes its aria-label. (316316@main) (180319221)

CSS

New Features

Added support for forwarding missing color components when interpolating between analogous color spaces. (315569@main) (180239320)

Added support for the no-clamp option on the CSS progress() function. (315977@main) (180473472)

Resolved Issues

Fixed serialization of various CSS at-rules not escaping identifiers. (315795@main) (178750383)

Fixed :last-child and related selectors incorrectly gating on parser state outside of style resolution. (316495@main) (178879939)

Fixed changing the color-scheme of an not invalidating the appearance of the embedded document. (316467@main) (179177141)

Fixed CSS scroll snap re-snap to prefer the fragment-targeted (:target) snap area over other aligned snap targets. (315880@main) (180108825)

Fixed the CSS preload scanner failing to preload @import rules that follow an @layer statement rule. (315576@main) (180170656)

Fixed serialization of CSSViewTransitionRule. (315614@main) (180170814)

Fixed MediaList.deleteMedium() to parse its argument as a media query and remove all matching queries. (315579@main) (180270019)

Fixed MediaList.appendMedium() to parse its argument as a single media query and suppress duplicates. (315594@main) (180291283)

Fixed grid items with stretch or fit-content preferred sizes computing incorrect minimum-content contributions when sizing tracks. (316296@main) (180748205)

Fixed inserting a CSS rule while a view transition is active causing the group animation to snap to its final state. (316436@main) (181100818)

Fixed CSS var() to only resolve its fallback when the first argument resolves to the guaranteed-invalid value. (316280@main) (181114298)

Fixed navigating away from a render-blocked document before its first rendering opportunity incorrectly firing pagereveal and starting an outbound cross-document view transition. (316446@main) (181191512)

Editing

Resolved Issues

Fixed drag images of DOM elements with CSS transforms not rendering correctly. (316077@main) (99614217)

Fixed opaque DOM mutations coming from dictation on iOS. (316049@main) (163454428)

Fixed deletion in an editable table leaving an empty trailing table row behind. (315990@main) (180877315)

Fixed vertical caret movement in editable content ignoring the requested editable-type parameter. (316241@main) (181000174)

Forms

Resolved Issues

Fixed the concentric inner-button corner radius on horizontal text form controls incorrectly ignoring the bottom inset. (316022@main) (180869927)

Images

Resolved Issues

Fixed a regression where RGB gain map images were decoded to 8 bits per channel, causing a color shift and incorrect brightness. (316069@main) (179152566)

Fixed handling of the gain-map target pixel format when decoding HDR images to fall back safely when the format cannot be parsed. (316405@main) (181180757)

JavaScript

New Features

Added support for the TC39 BigInt Math proposal, exposing Math-equivalent methods on BigInt such as BigInt.pow and BigInt.sqrt. (315974@main) (152472996)

Media

Resolved Issues

Fixed and controls rendering incorrectly when rotated via CSS transform. (315718@main) (37516619)

Fixed subtitles and closed captions not appearing in fullscreen video on iPhone. (315789@main) (175298523)

Fixed ArrayBuffer-backed YUV VideoFrame with a visibleRect rendering with offset chroma channels. (315742@main) (180202939)

Fixed video playback of streams from certain sources such as security cameras not working. (315774@main) (180411019)

Fixed transient device rotation resulting in captured video frames having the wrong orientation. (315821@main) (180429147)

Fixed Media Source Extensions playback and seek by loosening the gap tolerance between buffered ranges. (316146@main) (180439090)

Navigation

Resolved Issues

Fixed a to a URL differing only in fragment identifier being incorrectly treated as a page reload. (316001@main) (176933795)

Networking

Resolved Issues

Fixed URL path separators being encoded as %2F following a percent-encoded Armenian path segment. (315627@main) (180067095)

Rendering

Resolved Issues

Fixed the background of a composited element not being repainted when the background changed. (316415@main) (177975964)

Fixed a regression where block-axis padding on a flex column container with...