What's New in Safari Technology Preview 239: Accessibility, CSS, and Core Improvements
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<h2 id="table-of-contents">Table of Contents</h2>
<ul>
<li><a href="#accessibility">Accessibility</a></li>
<li><a href="#css">CSS</a></li>
<li><a href="#editing">Editing</a></li>
<li><a href="#forms">Forms</a></li>
<li><a href="#mathml">MathML</a></li>
</ul>
<p>Apple has released <strong>Safari Technology Preview 239</strong>, the latest iteration of its experimental browser, now available for download on macOS Tahoe and macOS Sequoia. If you already have the preview version installed, you can update it via <strong>System Settings → General → Software Update</strong>. This release includes WebKit changes from build <code>307619@main</code> to <code>308417@main</code>, delivering a wide range of bug fixes and a few feature additions. Below is a detailed look at what’s new and improved.</p><figure style="margin:20px 0"><img src="https://webkit.org/wp-content/themes/webkit/images/preview-card.jpg" alt="What's New in Safari Technology Preview 239: Accessibility, CSS, and Core Improvements" style="width:100%;height:auto;border-radius:8px" loading="lazy"><figcaption style="font-size:12px;color:#666;margin-top:5px">Source: webkit.org</figcaption></figure>
<h2 id="accessibility">Accessibility</h2>
<p>The accessibility team has tackled several <strong>VoiceOver</strong> issues, making Safari more inclusive for users who rely on screen readers.</p>
<h3>Resolved Issues</h3>
<ul>
<li><strong>SVG and unnamed images</strong>: Fixed an issue where SVG <code><use></code> elements referencing <code><symbol></code> inside an <code><img></code> were incorrectly treated as unnamed images in VoiceOver’s Images web rotor. (308126@main)</li>
<li><strong>Aria-owned rows in grids</strong>: VoiceOver could no longer access <code>aria-owned</code> rows and their cells within grids or tables—this has been resolved. (308087@main)</li>
<li><strong>Focusable splitter elements</strong>: Earlier, when navigating to the next or previous form control, VoiceOver missed focusable splitter elements. That gap is now closed. (308089@main)</li>
<li><strong>Aria-labelledby geometry</strong>: Controls using <code>aria-labelledby</code> now respect the native label’s geometry, even when both the control and its ARIA label lack a visible bounding box. (307727@main)</li>
</ul>
<h2 id="css">CSS</h2>
<p>CSS receives a notable new feature along with several important bug fixes that enhance layout accuracy.</p>
<h3>New Feature</h3>
<ul>
<li><strong>:open pseudo-class for inputs</strong>: Added support for the <code>:open</code> pseudo-class, allowing developers to style <code><input></code> elements based on their open state (e.g., when a date picker is expanded). (308148@main)</li>
</ul>
<h3>Resolved Issues</h3>
<ul>
<li><strong>Collapsed table borders</strong>: Tables with collapsed borders no longer spill extra border width into the margin area, because the first row’s width calculation is now correct. (308311@main)</li>
<li><strong>Inset box-shadow on table cells</strong>: Fixed incorrect positioning of <code>inset box-shadow</code> on table cells with collapsed borders. (307661@main)</li>
<li><strong>Subgrid intrinsic sizes</strong>: A subgrid (<code>display: grid</code> subgrids) inside grid-lanes containers no longer mistakenly contributes its child elements’ intrinsic sizes to the parent track sizing algorithm. (308253@main)</li>
<li><strong>Baseline calculation for inline-block</strong>: The baseline of inline-block elements now correctly falls to the bottom margin edge when <code>overflow</code> is not visible. (307718@main)</li>
<li><strong>Replaced element constraints</strong>: Replaced elements (like images and videos) now correctly apply <code>min-height</code> and <code>min-width</code> constraints in all configurations. (308212@main)</li>
<li><strong>Percentage heights in absolutely positioned elements</strong>: Children with percentage heights inside absolutely positioned containers using intrinsic height values (<code>fit-content</code>, <code>min-content</code>, <code>max-content</code>) now resolve correctly as <code>auto</code> instead of using the containing block’s height. (308226@main)</li>
</ul>
<h2 id="editing">Editing</h2>
<p>Two editing bugs have been squashed, improving the content creation experience.</p>
<h3>Resolved Issues</h3>
<ul>
<li><strong>FormatBlock and inline styles</strong>: Executing <code>execCommand('FormatBlock')</code> previously discarded the inline styles of replaced block elements, causing text formatting to vanish when pasting content. This is now preserved. (308365@main)</li>
<li><strong>Text-indent flickering</strong>: The <code>text-indent</code> property no longer flickers or is ignored when typing inside <code>contenteditable</code> elements. (307646@main)</li>
</ul>
<h2 id="forms">Forms</h2>
<p>A single but critical forms bug has been fixed.</p>
<h3>Resolved Issues</h3>
<ul>
<li><strong>Readonly date input</strong>: A <code>readonly</code> date <code><input></code> could still be edited via keyboard through the date picker—that loophole is now closed. (307934@main)</li>
</ul>
<h2 id="mathml">MathML</h2>
<p>MathML rendering receives improvements for dynamic content and positioning.</p>
<h3>Resolved Issues</h3>
<ul>
<li><strong>Attribute changes on <mo></strong>: Dynamic changes to attributes of the <code><mo></code> element now trigger a relayout, ensuring math operators stay in sync. (308014@main)</li>
<li><strong>Positioning of <mpresc</strong>: The positioning of the <code><mprescripts></code> element (a placeholder for scripts in MathML) has been corrected. (Further details pending from WebKit.)</li>
</ul>
<p>Safari Technology Preview 239 continues Apple’s commitment to refining the web platform, with a strong focus on accessibility, layout precision, and editing reliability. Developers and early adopters can download the update today and test these changes in their own projects.</p>
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