📃 September 2025 release notes

Newly available

The following features are newly available:

content-visibility: The content-visibility CSS property delays rendering an element, including layout and painting, until it is needed.
<link rel="dns-prefetch">: The rel="dns-prefetch" attribute for the <link> HTML element is a hint to the browser that the page or user is likely to request resources from another domain, so the browser should preemptively resolve DNS for the href value's domain.
Unsanitized HTML parsing methods: The Document.parseHTMLUnsafe() static method parses HTML into a DOM tree, while the setHTMLUnsafe() method of Element and ShadowRoot parses and inserts HTML into an existing tree. No sanitization applies to these methods, so never call them with user-provided HTML strings.
Uint8Array base64 and hex conversion: The Uint8Array object methods fromBase64(), toBase64(), and setFromBase64() convert to and from base64 strings. The fromHex(), toHex(), and setFromHex() methods convert to and from hex strings.
URLPattern: The URLPattern API creates patterns that can be matched against URLs or URL components.

Widely available

The following features are now widely available:

font-variant-alternates: The font-variant-alternates CSS property, along with the @font-feature-values at-rule, chooses when to use a font's alternate glyphs.
translate: The translate HTML attribute marks whether an element's text should be translated.
sin(), cos(), tan(), asin(), acos(), atan(), and atan2() (CSS): The sin(), cos(), tan(), asin(), acos(), atan(), and atan2() CSS functions compute various trigonometric functions.

New in Firefox

The following features are now available in Firefox:

::details-content: The ::details-content pseudo-element selects the expandable content of a <details> element, excluding the <summary>.

New in Firefox for Android

The following features are now available in Firefox for Android:

::details-content: The ::details-content pseudo-element selects the expandable content of a <details> element, excluding the <summary>.

New in Safari

The following features are now available in Safari:

Anchor positioning: Anchor positioning places an element based on the position of another element. For example, you can place a tooltip next to the content it references.
contrast-color(): The contrast-color() CSS function picks a color that has guaranteed contrast against a specified foreground or background color.
Scoped custom element registries: The CustomElementRegistry() constructor creates a new custom element registry that's separate from the global window.customElements registry. Creating more than one registry is useful for multiple custom elements that have the same tag name to coexist.
Scroll-driven animations: The animation-timeline, scroll-timeline, and view-timeline CSS properties advance animations based on the user's scroll position.
text-wrap: pretty: The text-wrap: pretty CSS declaration prioritizes better layout over speed when text is broken into multiple lines.
text-wrap-style: The text-wrap-style CSS property sets how lines break in text that overflows the container. It can also be set with the text-wrap shorthand.
Trusted types: Trusted types allow you to lock down insecure parts of the DOM API and prevent client-side cross-site scripting (XSS) attacks.
Web authentication signal methods: The signalUnknownCredential(), signalAllAcceptedCredentials(), and signalCurrentUserDetails() methods of PublicKeyCredential inform authenticators of the state of public key credentials, so that incorrect or revoked credentials may be updated, removed, or hidden.
WebCodecs: The WebCodecs API provides low-level access to individual video frames and chunks of audio samples, for full control over the way media is processed.
WebGPU: The navigator.gpu API performs operations such as rendering and computation on dedicated graphics hardware (also known as a Graphics Processing Unit).

New in Safari on iOS

The following features are now available in Safari on iOS:

Anchor positioning: Anchor positioning places an element based on the position of another element. For example, you can place a tooltip next to the content it references.
contrast-color(): The contrast-color() CSS function picks a color that has guaranteed contrast against a specified foreground or background color.
Scoped custom element registries: The CustomElementRegistry() constructor creates a new custom element registry that's separate from the global window.customElements registry. Creating more than one registry is useful for multiple custom elements that have the same tag name to coexist.
Scroll-driven animations: The animation-timeline, scroll-timeline, and view-timeline CSS properties advance animations based on the user's scroll position.
text-wrap: pretty: The text-wrap: pretty CSS declaration prioritizes better layout over speed when text is broken into multiple lines.
text-wrap-style: The text-wrap-style CSS property sets how lines break in text that overflows the container. It can also be set with the text-wrap shorthand.
Trusted types: Trusted types allow you to lock down insecure parts of the DOM API and prevent client-side cross-site scripting (XSS) attacks.
Web authentication signal methods: The signalUnknownCredential(), signalAllAcceptedCredentials(), and signalCurrentUserDetails() methods of PublicKeyCredential inform authenticators of the state of public key credentials, so that incorrect or revoked credentials may be updated, removed, or hidden.
WebCodecs: The WebCodecs API provides low-level access to individual video frames and chunks of audio samples, for full control over the way media is processed.
WebGPU: The navigator.gpu API performs operations such as rendering and computation on dedicated graphics hardware (also known as a Graphics Processing Unit).