Apple Releases Safari Technology Preview 188 – Brings Bug Fixes and Performance Improvements

Apple has released Safari Technology Preview 188, the latest version of their developer preview web browser. The preview version of Apple’s popular browser offers developers and other interested users the ability to try out features that may or may not, debut in future public release versions of Safari.

‌‌Safari Technology Preview‌ 188 includes fixes and updates for Accessibility, Animations, Browser Changes, CSS, Forms, Loading, Lockdown Mode, Media, Rendering, Scrolling, Storage, SVG, Web API, Web Extensions, WebAuthn, WebGL, and WebRTC.

The current ‌Safari Technology Preview‌ release is compatible with machines running macOS Ventura and macOS Sonoma.

Overview

Safari Technology Preview Release 188 is now available for download for macOS Sonoma and macOS Ventura. 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: 272449@main…273601@main.

Accessibility

New Features

• Added support for the new CSS content alternative text syntax. (272455@main) (26942023)

Resolved Issues

• Fixed role assignment for <header> inside <main> and sectioning elements. (273188@main) (48370244)
• Fixed text missing from accessibility labels for many common shadow DOM scenarios. (272531@main) (120223342)
• Fixed the mapping for the iOS accessibility framework to speak “switch button”, “on”, and “off” for <input type=checkbox switch>. (273206@main) (121215059)
• Fixed comboboxes to expose their linked objects correctly. (273542@main) (121242926)

Animations

Resolved Issues

• Fixed the transition property to produce the shortest serialization. (272513@main) (119822401)
• Fixed the animation property to produce the shortest serialization. (272629@main) (120439368)

Browser Changes

Resolved Issues

• Fixed loading a ⌘Click fragment link in a background tab. (272906@main) (119079650)
• Fixed saving linked subresources when saving web page resources. (272925@main) (120491493)

CSS

New Features

• Added supports() syntax for @import rules. (273591@main) (109060734)

Resolved Issues

• Fixed getComputedStyle() for invalid pseudo-elements. (272543@main) (98504661)
• Fixed oklab and oklch lightness value clamping. (272501@main) (116195533)
• Fixed poor performance with :has(+ :not(.class)) pseudo-class selector. (272678@main) (119819247)
• Fixed CSS content computed value serialization. (272476@main) (120061551)
• Fixed pseudo-element parsing in getComputedStyle() and KeyframeEffect.prototype.pseudoElement so they require them starting with :: (or : for 4 legacy pseudo-elements). (272499@main) (120170550)
• Fixed CSS linear() easing. (272613@main) (120290721)
• Fixed: Aliased :-webkit-full-screen pseudo-class to :fullscreen. (272577@main) (120335917)
• Fixed: Aliased :-webkit-any-link to :any-link and :matches() to :is(). (272559@main) (120337922)
• Fixed getComputedStyle() pseudo-element parsing to support the full range of CSS syntax. (272649@main) (120471227)
• Fixed :not(:has(:not(foo))) getting misclassified as scope breaking. (273177@main) (120492012)
• Fixed @supports to correctly handle support for some -webkit prefixed pseudo-elements that were incorrectly treated as unsupported. (272726@main) (120577690)
• Fixed updating media-query sensitive meta tags after style changes. (272947@main) (120854167)

Deprecations

• Removed -webkit-alt and alt properties. (272480@main) (120051066)
• Removed the non-standard resize: auto property. (273035@main) (120138995)
• Made -apple- prefixed pseudo-elements no longer valid. (272538@main) (120268884)
• Removed :-webkit-animating-full-screen-transition pseudo-class. (273529@main) (121302758)
• Removed :-khtml-drag pseudo-class. (273261@main) (121303391)

Forms

Resolved Issues

• Fixed text-indent to affect the selected file(s) label for file inputs. (272837@main) (105223868)

Loading

Resolved Issues

• Fixed navigator.cookieEnabled to return false when cookies are blocked. (273522@main) (121284878)

Lockdown Mode

Resolved Issues

• Fixed Lockdown Mode disabling on sites with COOP and COEP HTTP headers. (273243@main) (119503109)

Media

Resolved Issues

• Fixed HLS video captions where there are multiple text tracks available. (272784@main) (119839950)
• Fixed fullscreen video not scaling to display size when the Safari window is in Full Screen App Mode. (272733@main) (119893556)
• Fixed handling key renewal requests that cause playback errors for some DRM content. (272592@main) (120230860)
• Fixed paint-on captions shifting during playback. (272966@main) (120847946)
• Fixed blocked encrypted sampled not getting enqueued after a CDM is attached to a SourceBuffer. (273340@main) (120879185)

Rendering

Resolved Issues

• Fixed resizing a <textarea> element with 1rem padding. (273029@main) (90639221)
• Fixed incorrectly oriented Traditional Mongolian script characters. (272454@main) (93426525)
• Fixed handling images with color spaces not supported by the backend to fallback to render in sRGB. (273204@main) (118238178)
• Fixed check boxes and radio buttons to avoid floats. (273047@main) (118660695)
• Fixed rendering issues when editing text. (273320@main) (119833765)
• Fixed a floating element causing a list item bullet to be orphaned on constrained lines. (272451@main) (120022893)
• Fixed fully repainting form controls with visual overflow and writing-mode: vertical-rl. (272799@main) (120066970)
• Fixed incorrect inline box (hugging) outline painting in vertical writing modes. (272512@main) (120217559)
• Fixed incorrect ch unit value in vertical-rl and vertical-lr when text-orientation is not upright. (272536@main) (120293590)
• Fixed the color correctness of the color matrix filter. (272891@main) (120795573)
• Fixed overflow: hidden preventing CSS Subgrid. (273134@main) (120848131)
• Fixed the repaint area for underline text decorations. (273126@main) (121082290)
• Fixed rendering floats and an out-of-flow <br> element with clear. (273407@main) (121444267)

Scrolling

Resolved Issues

• Fixed unusable horizontal scrollbars with a right-to-left element. (272466@main) (109858866)
• Fixed wheel overflow behavior with Shadow DOM elements. (273181@main) (118496293)
• Fixed keyboard scrolling beyond the page getting stuck at a bad scroll offset. (272957@main) (120053910)
• Fixed a variety of issues by disabling Scroll Anchoring. (273238@main) (121236706)

Storage

Resolved Issues

• Fixed cases where website data is unexpectedly evicted. (272951@main) (119818267)

Deprecations

• Removed support for AppCache. (273297@main) (113343269)

SVG

Resolved Issues

• Fixed negative SVGTransform scale values to be correctly stringified. (272885@main) (118656892)
• Fixed the layout of an SVG when it is inside an <iframe> without affecting the size of the <iframe>. (272503@main) (120178866)
• Fixed displaying an SVG element inside a <switch> element. (272831@main) (120732837)

Web API

New Features

• Added support for CustomStateSet in custom elements and :state() pseudo-class. (272474@main) (120072599)

Resolved Issues

• Fixed: Added support for AES-GCM in WebCrypto. (273488@main) (101040216)
• Fixed removing highlights in the Custom Highlights API. (272723@main) (119531671)
• Fixed unnecessarily unsetting the iframe fullscreen flag. (272462@main) (120052751)
• Fixed getElementsByName() to only return HTML elements, not SVG, MathML, or other types of elements. (272530@main) (120275680)
• Fixed the button value for a pointerup event not matching the pointerdown event. (273263@main) (120429508)
• Fixed a wheel event to fire on an element that has been re-inserted after document.open. (272960@main) (120893136)
• Fixed Scroll To Text Fragment Text Directives to find text with additional unrendered white space in their node data. (273016@main) (120913588)
• Fixed Media Capture API to capture the camera. (273258@main) (121256297)

Deprecations

• Removed support for KeyboardEvent.altGraphKey. (273379@main) (102980723)
• Removed AES-CFB support from WebCrypto. (272615@main) (120000331)
• Removed the non-standard KeyboardEvent.keyLocation. (273457@main) (121564228)

Web Extensions

Resolved Issues

• Fixed browsing.scripting.executeScript to handle all valid argument types. (120727491)

WebAuthn

Resolved Issues

• Fixed getClientCapabilities to align with WebAuthn standards to use a record type with camelCase values. (272998@main) (120442670)

WebGL

New Features

• Enabled support for EXT_conservative_depth and NV_shader_noperspective_interpolation. (272979@main) (120907578)

Resolved Issues

• Fixed WebGL to be available in nested workers. (272765@main) (120279728)

WebRTC

Resolved Issues

• Fixed triggering resolution scaling in the case of WebRTC maintain-framerate degradationPreference. (273172@main) (121041723)

While the preview is intended for use by developers and advanced users, to provide Apple with feedback on the development of the Safari browser, it can be run side-by-side with the release version of Safari. The app doesn’t require a developer account to download and install. For more information, visit the Safari Technology Preview website.