CSS Database is a comprehensive list of CSS features and their positions in the process of becoming implemented web standards. These positions reflect the TC39 process.

Did you come here to update the status of a CSS feature or add a new one? Quick, read our CONTRIBUTING.md.

This staging process reflects the real-life stability of new CSS features.

You can read an inside view of the CSSWG to learn about the official (and unofficial) development stages of CSS specifications. In reality, specifications and browser implementations happen out of sync. Stable CSS features are missing in all browsers, while other CSS features developed outside the CSSWG are already behind flags in Chrome. This is too ambiguous for the web development community, and a more accountable process is desired.

A CSS specification presented to the CSSWG by a champion within or outside the CSSWG. It should be considered highly unstable and subject to change.

A CSS specification formally endorsed by the CSSWG. It should be considered highly unstable and subject to change.

A CSS specification formally endorsed by the CSSWG and requiring implementations to move forward. It should be considered stable and subject to little change.

A CSS specification formally endorsed by the CSSWG and being implemented by recognized browser vendors, possibly behind a flag. It should be considered stable and subject to little change.

A CSS specification formally endorsed by the CSSWG and implemented by all recognized browser vendors.

This is any specification that has not yet been presented to the CSSWG, or that has been formally rejected or deprecated by the CSSWG.

Recognized browser vendors include, in alphabetical order; Apple, Google, Microsoft, Mozilla, and Opera.

A champion is the person responsible for advocating a new CSS feature to completion, performing the legwork necessary to ensure the concerns of interested CSSWG members are identified and incorporated into the proposal.