Tested this against current develop. The branch here is very behind, but the one-line change cherry-picks clean and the target line is unchanged upstream, so it still applies as-is.

Reproduced the bug first: built a Character Count whose input uses a React useId()-style id (:r0:), and CharacterCount.on() throws exactly what the issue reports:

SyntaxError: 'label[for=character-count-:r0:]' is not a valid selector

With this PR's change (label[for="${inputID}"]) the same setup initializes cleanly. So the fix does what it says.

Worth flagging why this isn't an edge case: :r0: is literally what React 18+'s useId() emits, and pairing useId() across the input and its <label for> is the existing pattern. Any React/Next consumer wiring Character Count up that way hits it.

Two small things, neither a blocker:

• Quoting handles every id that's valid HTML, which is the actual bug here. If you wanted to be bulletproof against an id containing a literal " or \, CSS.escape(inputID) is the belt-and-suspenders version, but that's beyond what's reported.

✅ All commits on this PR now have a verified signature. Thanks for making that change!