🐞 incorrect syntax highlighting for `bg:`

### Description

![image](https://github.com/master-co/css/assets/33840671/55e52fe6-374a-4eb4-9d27-0e1979bf296d)

- `.png` was misparsed as a selector.
- `|` should be gray.

### Reproduction

_No response_

### System Informations

_No response_