We've loved seeing folks post their rankings, so we've added a share button!
You can either share your list via the site directly, or copy your list as markdown/html for your own blog.
We ran this last year to decide what to champion for Interop 2026, but the data was so good, we also used it to prioritise features beyond the Interop project.
We've also added some features to make it quicker to rank items.
What do you want us to work on in 2027?
Here's a web app where you can rank the Interop proposals you care about, giving us data we can use to prioritise feature development.
Firefox 157 has landed, and includes a couple of useful CSS features:
🎉 at-rule() in @supports - lets you limit rules to browsers that support a given at-rule.
🎉 overscroll-behavior: chain - lets scrolling pass up to parent elements, but prevents UA effects like 'bounce' and overscroll.
…And more! https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/157
When and how CSS custom property values are calculated might not be what you expect, and it has a big impact on your styles…
When and how CSS custom property values are calculated might not be what you expect, and it has a big impact on your styles…
The CSS progress() function is now in all major engines! Here's how it works:
Interop 2027 is open for proposals! Is there a well-tested feature that you'd like to see cross-browser focus on next year? Submit it here: https://github.com/web-platform-tests/interop/blob/main/proposal_guide.md
CSS attr() now works on all properties in Firefox 155. Here's how it works, and how to get the most out of it:
The full docs on MDN: https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Values/attr
Major versions of Firefox now land every two weeks, so Firefox 155 dropped today with web platform features including:
🎉 Fully typed CSS attr()
🎉 CSS progress()
🎉 CSS alpha()
🎉 Promise.allKeyed() and allSettledKeyed()
🎉 Wasm wide arithmetic
🎉 Lots of new WebTransport stuff
…And more!
https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/155
CSS sibling-count() and sibling-index() are newly available across engines! Here's how they work:
And the full docs on MDN: https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Values/sibling-index
JPEG XL is slated to ship in Firefox 157 next month! Here's how we're shipping it safely… https://hacks.mozilla.org/2026/08/intent-to-ship-jpeg-xl/
Chrome also has an Intent to Ship, so support should land in both browsers within a week of each other https://groups.google.com/a/chromium.org/g/blink-dev/c/-gDojQbDPRI
Intent to ship: JPEG XL! This will be on-by-default in Firefox 157, which should become the main release version at the end of September.
This includes key JPEG XL features like progressive rendering.
https://groups.google.com/a/mozilla.org/g/dev-platform/c/3YMV4MS34KA
In a JPEG XL compatible browser (like Firefox Nightly), test how it renders progressively by moving the slider in this demo: https://random-stuff.jakearchibald.com/apps/partial-img-decode/?demo=fox-progressive.jxl&density=2
What should happen with text-box-trim and margin-trim when it comes to negative values? Do negatives 'trim'?