The following subselector construction does not work. It’s browser-independent.

body:has(.container:has(p))

You can test it on Google

Add the following CSS (e.g. using Stylus for Chrome / Firefox) with the following CSS code:

body:has(form) {background:#ff000055}

body:has(textarea) {transform: rotatez(2deg)}

body:has(form:has(textarea)) {background:#00ff0055}

• ✓ The first line is confirmed by the rotation, so it works.

• ✓ The second line is confirmed by the red background, so it works.

• ✕ But we should see a green background instead of red, because of the third line overrides it, so the nested form doesn’t work. (Just remove the first line with the red background.)

Obviously, it should work, even on multiple levels.

Where could I report it? I didn’t find a ‘Bug Report’ option on W3.org.