Published: September 11, 2025
August has come and gone, and with it, more has happened with Baseline—including some notable developments!
CSS container queries are now Baseline Widely available
CSS container queries landed in all major browser engines in 2023. They represent a major change from media queries in terms of how page styles can be changed in different contexts. Media queries let you change styles based on the dimensions of the device's screen, container queries let you change styles based on the dimensions of an element. This provides many practical benefits in terms of style encapsulation and developer experience—and as of August, container queries have become Baseline Widely available!
If you're new to container queries, we've recently updated Learn CSS with new modules—including a module on container queries. It's a great resource to learn how to use this exciting feature, that the majority of sites should now be confident in adopting.
Other features that became Baseline in August
Container queries weren't the only things that became Baseline Widely available in August this year. The following two features also became Widely available:
On top of this, selection composed ranges became Baseline Newly available in August.
MDN launches a new frontend with a focus on Baseline
Recently, Mozilla launched a new frontend for MDN that was completely redesigned and reengineered from scratch. The new frontend offers several UI improvements from readability, search improvements, and more.
When building the new frontend, MDN used Baseline as a basis for determining which features made the most sense to use by intentionally targeting Widely available features. As for other features that aren't Widely available, MDN made the call on a case-by-case basis to adopt polyfills or use progressive enhancement where practical. MDN will eventually publish a follow-up post with technical details on how they built their new frontend, so keep an eye out for that!
The Baseline tooling hackathon is on!
Though this technically didn't happen in August, it's worth mentioning that the Baseline tooling hackathon began at the beginning of this month. This hackathon goes on until October 6th, and the prizes are:
- First prize: $5,000
- First prize: $3,000
- Third prize: $1,000
- Most valuable feedback (10 winners): $100 each
Plus, the top three winners will be featured here on the web.dev blog, and get a 30 minute private feedback and strategy session with the Chrome team. For more information and how to register, read our blog post on the hackathon.
That's a wrap
That's another month in the books for Baseline—and as usual, let us know if we missed anything Baseline-related, and we'll make sure it gets captured in a future edition. See you in a month!