Safari Technology Preview 240: New Features and Bug Fixes Explained
Apple has released Safari Technology Preview 240, bringing a fresh batch of enhancements and corrections to macOS Tahoe and macOS Sequoia. This update focuses on refining CSS capabilities, squashing bugs in editing, forms, HTML parsing, and media handling. If you're already running a previous version, updating is straightforward via System Settings. Below, we dive into the key changes and answer common questions about this release.
How can I download or update Safari Technology Preview 240?
You can obtain Safari Technology Preview 240 by visiting the official downloads page for macOS Tahoe or macOS Sequoia. If you already have a prior version installed, updating is simple: open System Settings, navigate to General, then Software Update. The update will appear there—just click to install. This release incorporates all WebKit improvements from changes between 308418@main and 309286@main. It's a free update for anyone with a compatible Mac.
What CSS improvements are in this release?
Several CSS enhancements landed in Safari Technology Preview 240. A major new feature is support for the revert-rule keyword. This allows developers to roll back the cascade as if the current style rule never existed, offering finer control over inherited styles. On the bug-fix side, a macOS-specific issue where custom CSS scrollbars were cut off has been resolved. Additionally, the hanging-punctuation property now correctly handles apostrophes (U+0027) and quotation marks (U+0022) as hangable characters. It also allows ideographic space (U+3000) to hang when used with the first value. These changes make web pages more consistent and visually polished.
What editing issues were resolved?
Three notable editing bugs have been fixed. First, the Font Picker no longer becomes unusable after changing fonts while editing multiple lines of text. Second, emoji images are now preserved correctly when copying and pasting content across different websites, preventing broken or missing icons. Third, an issue where text selection would jump unexpectedly has been addressed—this occurred when selecting absolutely-positioned content inside an element with user-select: none. These fixes improve the reliability of rich text editing and cross-site content handling, especially in web applications that rely on custom selection behavior.
What form-related fix was made?
A single but impactful form bug was squashed: when a button gained focus via keyboard tabbing and then became disabled, the focus would jump to the very beginning of the page, disrupting the user's flow. This is now resolved, so tabbing order remains logical even when buttons are dynamically disabled. This fix enhances accessibility and ensures that keyboard navigation behaves as expected in forms.
What HTML parsing issues were fixed?
Two HTML parsing issues were corrected. First, the viewport <meta> tag now correctly treats form feed characters as ASCII whitespace, aligning with the HTML specification. Second, pixel-length margin attributes on <body>, <iframe>, and <frame> elements are no longer incorrectly parsed. These changes improve compatibility with standards and prevent rendering anomalies in pages that use these attributes.
What media-related bugs were addressed?
This release fixes multiple media bugs. Important fixes include: decoding WebM audio files with more than two channels now works; MediaCapabilities.decodingInfo() correctly reports VP8 in WebM as supported; MP4 files with Opus audio tracks can be decoded with decodeAudioData; Live Text selection is available on paused fullscreen videos; FairPlay-protected VP9 content plays via MediaSource; autoplay waits for default text tracks to finish loading; currentTime getter returns defaultPlaybackStartPosition when no media player exists; HTMLMediaElement fires a timeupdate event when resetting playback position during load; and the media player preload attribute behavior is corrected. These updates enhance video playback, audio decoding, and streaming reliability.