10 Key Updates in Safari Technology Preview 240 You Should Know
Safari Technology Preview 240 brings a host of improvements to web developers and users. This release refines CSS cascade control, fixes editing quirks, and resolves numerous media playback issues. Below, we unpack the ten most significant changes that will enhance your browsing and development experience. Whether you're a front-end engineer or a power user, these updates matter.
1. New CSS Revert-rule Keyword
The revert-rule keyword is now supported, allowing you to roll back the cascade for a specific style rule. This means you can effectively undo the effects of a rule as if it never existed in the cascade. It’s particularly useful when overriding styles in complex stylesheets or when you need to reset a property without using unset or initial. This addition gives developers more granular control over CSS inheritance and specificity.
2. Hanging Punctuation Fixes
Two issues with hanging-punctuation have been resolved. First, the apostrophe (U+0027) and quotation mark (U+0022) are now correctly treated as hangable quotes. Second, ideographic space (U+3000) can now hang when used with the first value. These fixes ensure that punctuation hangs properly in East Asian and Western typography, improving text layout and readability.
3. Font Picker Usability Restored
An annoying bug in the Font Picker has been squashed: changing fonts while editing multiple lines of text no longer makes the style selection unusable. Previously, interacting with the font picker would break subsequent style changes, forcing developers to reload the page. Now you can switch fonts freely within rich text editors without unexpected behavior.
4. Emoji Copy-Paste Preserved Across Sites
Copying and pasting content containing emoji images between different websites used to lose those images. This release fixes that issue, ensuring emoji are preserved correctly when transferring content across domains. This is crucial for messaging apps, forums, and any platform that relies on emoji in user-generated content.
5. Smoother Text Selection in Absolute Positioning
When selecting text inside absolutely-positioned elements that are nested within a user-select: none container, the selection no longer jumps unexpectedly. This fix brings sanity to complex layout scenarios where precise text selection is required, such as in code editors or drag-and-drop interfaces.
6. Keyboard Focus Retained on Disabled Buttons
A frustrating accessibility bug has been resolved: when a focused button becomes disabled, the keyboard tabbing position no longer jumps to the top of the page. Instead, the focus remains logically near the button, maintaining a natural flow for keyboard navigation. This improvement benefits users who rely on keyboard-only browsing.
7. Viewport Meta Parsing Alignment
The <meta viewport> parser now correctly treats form feed as ASCII whitespace, matching the HTML specification. This minor but important change ensures that viewport meta tags with unconventional spacing (e.g., using form feeds) are parsed consistently across browsers, leading to more predictable responsive behavior.
8. Corrected Pixel-Length Margin Attributes
Pixel-length margin attributes on <body>, <iframe>, and <frame> were previously parsed incorrectly. This fix ensures that values like marginwidth="10" are interpreted as exact pixel lengths rather than being ignored or miscalculated. It solves legacy layout issues, especially in pages that rely on these older attributes.
9. Better WebM Audio and VP8 Support
Two WebM-related issues are addressed: decoding WebM audio files with more than two channels now succeeds, and MediaCapabilities.decodingInfo() no longer falsely reports VP8 in WebM as unsupported. These fixes expand WebM compatibility, enabling smoother playback of multi‑channel audio and more accurate media capability reporting.
10. Media Playback and Timing Improvements
This release tackles several media quirks: MP4 files with Opus audio can now be decoded via decodeAudioData, Live Text selection works on paused fullscreen videos, FairPlay-protected VP9 content plays through MediaSource, autoplay waits for default text tracks to load, currentTime returns defaultPlaybackStartPosition correctly, and a missing timeupdate event is fired when resetting playback position. These collectively enhance media reliability and standards compliance.
In summary, Safari Technology Preview 240 delivers targeted fixes that polish the browsing and development experience. From CSS cascade tools to media playback stability, these updates reflect Apple’s commitment to web standards and performance. If you haven’t updated yet, head to System Settings > General > Software Update to download the latest preview.