New to the web platform in August

Discover some of the interesting features that have landed in stable and beta web browsers during August 2026.

Rachel Andrew

Published: August 28, 2026

Stable browser releases

Chrome 152 and Firefox 154 released to stable during August 2026. There was no new Safari stable release this month. This post takes a look at the new features landing across the web platform. It's been an excellent month for features becoming Baseline Newly available.

Note: Browser compatibility data pulled from MDN is included in these posts and may not have been updated yet for very recent browser releases. The post will show the correct information as soon as it appears in the browser-compat-data release.

The text-box properties become Baseline

Firefox 154 introduces support for text-box-trim, text-box-edge, and the text-box shorthand property.

These properties give you fine-grained control over text alignment and spacing in the block direction. Font metrics often include extra vertical space above and below glyphs (leading and half-leading), which can make vertical alignment uneven and cause unexpected spacing around headings or icons.

The text-box-edge property specifies the font metrics to trim to (such as cap alphabetic or ex alphabetic), and text-box-trim specifies whether to trim the over edge, under edge, or both. The text-box shorthand combines both properties.

With support in Safari 18.2, Chrome 133, and now Firefox 154, the text-box properties are now Baseline Newly available.

Browser Support

• 133
• 133
• 154
• 18.2

Source

The sibling-count() and sibling-index() CSS functions become Baseline

Firefox 154 adds support for the sibling-count() and sibling-index() CSS functions.

The sibling-count() function returns an integer representing the total number of sibling DOM elements in the parent container (including the element itself). The sibling-index() function returns the 1-based position of the current element among its siblings.

These functions let you calculate layout sizes, staggered animation delays, and color variations dynamically in CSS without needing JavaScript or utility classes. They are now Baseline Newly available.

Browser Support

• 138
• 138
• 154
• 26.2

Source

The autocorrect global HTML attribute becomes Baseline

Chrome 152 adds support for the global autocorrect HTML attribute and reflects it on HTMLElement.prototype.autocorrect.

The autocorrect attribute lets you control whether automatic spelling and punctuation correction is enabled on editable elements, including <input>, <textarea>, and elements with contenteditable. It accepts on and off.

With Safari and Firefox already supporting this attribute, the global autocorrect attribute is now Baseline Newly available.

Browser Support

• x
• x
• 136
• 14.1

Source

CSSPseudoElement support for ::backdrop, ::scroll-marker, and ::view-transition

Chrome 152 extends CSSPseudoElement support (previously available for ::after, ::before, and ::marker) to include ::backdrop, ::scroll-marker, and ::view-transition.

Supporting CSSPseudoElement for ::backdrop lets you attach event listeners directly to the backdrop pseudo-element, making it straightforward to close a dialog when clicking outside the dialog content without computing coordinate bounding boxes. For ::scroll-marker, it facilitates capturing user interaction events, and for ::view-transition, it enables intercepting transitions or building geometry-aware animations.

Browser Support

• 149
• 149
• 
• x

Source

Relative alpha colors with the alpha() CSS function

Chrome 152 introduces the alpha() function from CSS Color 5 for relative alpha colors.

The alpha() function takes an existing origin color and returns that color with an adjusted alpha (transparency) channel, preserving the color channels and working seamlessly in any color space:

Browser Support

• 151
• 151
• 
• 27

Source

The window-drag CSS property

Chrome 152 adds support for the standard window-drag CSS property.

When developing installed desktop web applications, you can use window-drag to designate specific areas of your layout—such as custom title bars or headers—as draggable regions. Pointer drag gestures on these regions move the top-level application window rather than scrolling or selecting page content. This standardizes and renames the older app-region property, using values move and none with standard CSS inheritance.

Browser Support

• 
• x
• x
• x

The OpaqueRange API

Chrome 152 introduces OpaqueRange, representing a live text range within form control values such as <textarea> and text-based <input> elements.

OpaqueRange enables range-based APIs, including getBoundingClientRect(), getClientRects(), and the CSS Custom Highlight API, to operate on form control text for inline suggestions, spelling highlights, and anchored popovers. It maintains component encapsulation by exposing value offsets rather than internal shadow tree container nodes.

New Iterator helper methods in Firefox

Firefox 154 adds several new methods to Iterator.prototype:

• includes(): Checks whether an iterator produces a specified value, returning true or false.
• join(): Concatenates all elements produced by the iterator into a string separated by a delimiter, similar to Array.prototype.join().
• chunks(): Returns a helper iterator that yields consecutive fixed-size array chunks from the underlying iterator.
• windows(): Returns a helper iterator that yields a sliding window array over the iterator.

Browser Support

• x
• x
• 154
• x

Source

WebRTC transport improvements in Firefox

Firefox 154 introduces several WebRTC transport additions:

• RTCIceTransport.getSelectedCandidatePair() and the selectedcandidatepairchange event, allowing applications to inspect the currently active ICE candidate pair.
• The error event on RTCDtlsTransport, allowing applications to listen for DTLS transport and fingerprint errors.
• Support for the rtcp configuration parameters on RTCRtpReceiver.getParameters() and RTCRtpSender.getParameters().
• WebRTC transport statistics, reporting RTCCertificateStats and additional RTCTransportStats.

With support in Chrome, Safari, and now Firefox 154, RTCIceTransport.getSelectedCandidatePair() and the RTCDtlsTransport error event are now Baseline Newly available.

Browser Support

• 75
• 79
• 154
• 16.4

Source

Beta browser releases

Beta browser versions give you a preview of features coming in the next stable version of the browser. It's an ideal time to test new features or check for breaking changes before they reach all users. New betas this month are Chrome 153 and Firefox 155. There is no Safari beta this month.

Chrome 153 beta includes single-axis scroll containers (overflow: scroll clip) and the scroll-axis-lock CSS property to prevent gesture axis locking. On the JavaScript side, it adds TC39 Iterator join() and joint iteration (zip). Web API additions include dedicated single-capability declarative elements <camera> and <microphone>.

Firefox 155 beta updates SVGAElement to implement HyperlinkElementUtils, exposing standard URL properties (protocol, hostname, pathname, search, hash) and origin on SVG <a> elements. It also adds indexed setters to SVG list interfaces (SVGNumberList, SVGPointList, SVGStringList, SVGTransformList).