Code selection not visible in Safari

[pskelin]

When I open the code editor in Safari, text selection is not visible even though it is applied. For example, open
https://lit.dev/playground/

Then select a word with double click -> nothing is visualised, but backspace deletes it.

Safari 17.3.1 (19617.2.4.11.12)
MacOS Sonoma 14.3.1 (23D60)

[e111077]

should be fixed by #421