New to the web platform in November

Discover some of the interesting features that have landed in stable and beta web browsers during November 2023.

Rachel Andrew

Stable browser releases

In November 2023, we only had one stable browser release with Firefox 120. This post looks at what that means for the web platform.

Support for the media attribute in the <source> element

Firefox reintroduces support for the media attribute in the <source> element. The support is expanded to include the <audio> and <video> elements. With this release, the media attribute will be available in <source> elements within <audio>, <video>, and <picture>.

Support for the media attribute is coming to Chrome, and is already in Safari, so you will soon have support for responsive HTML video and audio across all engines.

The CSS Color light-dark() function

Firefox now supports the light-dark() CSS Color function. This means that you can set colors for light and dark schemes without using the prefers-color-scheme media feature.

Browser Support

  • 123
  • 123
  • 120
  • 17.5

Source

The lh and rlh units

Firefox supports the CSS units lh and rlh These units allow you to set values relative to the line-height of an element, this is useful when you want to align background images with text. This release makes these unts interoperable across all three major engines.

Browser Support

  • 109
  • 109
  • 120
  • 16.4

HTTP 103 Early Hints

Firefox now supports the 103 Early Hints HTTP information response status code.

Browser Support

  • 103
  • 103
  • 120
  • 17

Source

Beta browser releases

Beta browser versions give you a preview of things that will be in the next stable version of the browser. It's a great time to test new features, or removals, that could impact your site before the world gets that release. New betas are Firefox 121, Chrome 120, and Safari 17.2. These releases bring many great features to the platform. Check out the release notes for all of the details. Here are just a few highlights.

Chrome 120 and Safari 17.2 include relaxed parsing for CSS Nesting.

Chrome 120 unprefixes the -webkit-mask* properties and brings them into line with the current specification. This includes mask-image, mask-mode, mask-repeat, mask-position, mask-clip, mask-origin, mask-size, and mask-composite, as well as the mask shorthand. Local mask-image references are supported, serialization now matches the specification, and accepted values now match the specification.

Chrome 120 and Safari 17.2 include support for the name attribute for the <details> element.

Firefox 121 includes the CSS :has() selector. This release makes :has() interoperable across all major engines.

Part of the New to the web series