Does not support transparent hex colours (#RRGGBBAA)

The result is an incorrect highlight for a [hex colour](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Values/hex-color) with transparency component.


<img width="279" height="65" alt="Image" src="https://github.com/user-attachments/assets/c7fa0c75-aba7-478f-a89f-2446078635ad" />