In #12775 (comment) I was requested to go through Selectors 4 and check for additional features that could be added to the Save to Release pre-CR Exceptions Section of the CSS Snapshot 2025.

Given the outdated Changes section, I didn't realize how many selectors were actually added in level 4 (and widely implemented). It is a bunch! Here's a list of the ones that could potentially be added to the Safe to Release section:

:scope

• implemented in all major browsers since 2014
• WPT: passing tests: Chrome: 17, Edge: 17, Firefox: 17, Safari: 17; interop: 17 / 17 (100%)
• Open issues: on GitHub: 3, in spec.: 0

:defined

• implemented in all major browsers since 2020
• WPT: passing tests: Chrome: 2, Edge: 2, Firefox: 2, Safari: 2; interop: 2 / 2 (100%)
• Open issues: on GitHub: 0, in spec.: 0

:focus-visible

• implemented in all major browsers since 2020
• WPT: passing tests: Chrome: 148, Edge: 148, Firefox: 191, Safari: 130; interop: 125 / 193 (64.8%)
• Open issues: on GitHub: 6, in spec.: 0

:focus-within

• implemented in all major browsers since 2020
• WPT: passing tests: Chrome: 32, Edge: 32, Firefox: 32, Safari: 24; interop: 24 / 32 (75%), interop between Chrome, Edge, and Firefox: 32 / 32 (100%)
• Open issues: on GitHub: 0, in spec.: 0

:dir()

• implemented in all major browsers since 2023
• WPT: passing tests: Chrome: 73, Edge: 73, Firefox: 73, Safari: 73; interop: 73 / 73 (100%)
• Open issues: on GitHub: 1, in spec.: 0

:any-link

• implemented in all major browsers since 2020
• WPT: passing tests: Chrome: 2, Edge: 2, Firefox: 2, Safari: 2; interop: 2 / 2 (100%)
• Open issues: on GitHub: 0, in spec.: 0

:open

• implemented in Chrome, Edge, and Firefox since 2025
• WPT: passing tests: Chrome: 7, Edge: 7, Firefox: 7, Safari: 2; interop: 2 / 7 (28.6%), interop between Chrome, Edge, and Firefox: 7 / 7 (100%)
• Open issues: on GitHub: 0, in spec.: 0

:popover-open

• implemented in all major browsers since 2023
• WPT: passing tests: Chrome: 1, Edge: 1, Firefox: 1, Safari: 1; interop: 1 / 1 (100%)
• Open issues: on GitHub: 0, in spec.: 0

:modal

• implemented in all major browsers since 2022
• WPT: passing tests: Chrome: 7, Edge: 7, Firefox: 7, Safari: 7; interop: 7 / 7 (100%)
• Open issues: on GitHub: 0, in spec.: 0

:fullscreen

• implemented in all major browsers since 2022
• WPT: passing tests: Chrome: 2, Edge: 2, Firefox: 2, Safari: 2; interop: 2 / 2 (100%)
• Open issues: on GitHub: 0, in spec.: 0

:picture-in-picture

• implemented in Chrome, Edge, and Safari since 2023
• WPT: no tests
• Open issues: on GitHub: 0, in spec.: 0

:read-only

• implemented in all major browsers since 2020
• WPT: no tests
• Open issues: on GitHub: 0, in spec.: 0

:read-write

• implemented in all major browsers since 2020
• WPT: passing tests: Chrome: 2, Edge: 2, Firefox: 2, Safari: 2; interop: 2 / 2 (100%)
• Open issues: on GitHub: 0, in spec.: 0

:placeholder-shown

• implemented in all major browsers since 2020
• WPT: passing tests: Chrome: 16, Edge: 16, Firefox: 16, Safari: 13; interop: 13 / 16 (81.3%), interop between Chrome, Edge, and Firefox: 16 / 16 (100%)
• Open issues: on GitHub: 0, in spec.: 0

:autofill

• implemented in all major browsers since 2023
• WPT: no tests
• Open issues: on GitHub: 0, in spec.: 0

:default

• implemented in all major browsers since 2023
• WPT: passing tests: Chrome: 6, Edge: 6, Firefox: 4, Safari: 6; interop: 4 / 6 (66.7%), interop between Chrome, Edge, and Safari: 6 / 6 (100%)
• Open issues: on GitHub: 0, in spec.: 0

:indeterminate

• implemented in all major browsers since 2015
• WPT: no tests
• Open issues: on GitHub: 1, in spec.: 0

:valid

• implemented in all major browsers since 2015
• WPT: no tests
• Open issues: on GitHub: 0, in spec.: 0

:invalid

• implemented in all major browsers since 2015
• WPT: no tests
• Open issues: on GitHub: 0, in spec.: 0

:in-range

• implemented in all major browsers since 2015
• WPT: no tests
• Open issues: on GitHub: 0, in spec.: 0

:out-of-range

• implemented in all major browsers since 2015
• WPT: no tests
• Open issues: on GitHub: 0, in spec.: 0

:required

• implemented in all major browsers since 2015
• WPT: passing tests: Chrome: 3, Edge: 3, Firefox: 3, Safari: 3; interop: 3 / 3 (100%)
• Open issues: on GitHub: 0, in spec.: 0

:optional

• implemented in all major browsers since 2015
• WPT: passing tests: Chrome: 3, Edge: 3, Firefox: 3, Safari: 3; interop: 3 / 3 (100%)
• Open issues: on GitHub: 0, in spec.: 0

:user-valid

• implemented in all major browsers since 2023
• WPT: passing tests: Chrome: 8, Edge: 4, Firefox: 4, Safari: 5; interop: 4 / 8 (50%)
• Open issues: on GitHub: 2, in spec.: 0

:user-invalid

• implemented in all major browsers since 2023
• WPT: passing tests: Chrome: 11, Edge: 7, Firefox: 8, Safari: 9; interop: 7 / 11 (63.6%)
• Open issues: on GitHub: 2, in spec.: 0

Wildcards and language code matching in :lang()

• implemented in Firefox and Safari since 2023
• WPT: passing tests: Chrome: 77, Edge: 76, Firefox: 74, Safari: 74; interop: 74 / 77 (95.9%)
• Open issues: on GitHub: 4, in spec.: 0

Selector lists in :nth-child() and :nth-last-child()

• implemented in all major browsers since 2023
• WPT: passing tests: Chrome: 29, Edge: 29, Firefox: 29, Safari: 29; interop: 29 / 29 (100%)
• Open issues: on GitHub: 1, in spec.: 0

Sebastian

PS: Given the huge list of features that are already shipping, I wonder if we should move the rest to level 5, so level 4 can move to CR. I'll create a separate issue for that.