Highlight.js horizontal scroll bar disappears in dark mode

[OCram85]

Description

The scroll bard in code blocks with large content disappears in dark mode.

Steps to reproduce

use any code block like this:

Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores 

Expected result

Switching to dark mode should keep the scroll bar visible regardless. I'm using the highlight.js theme, but the color needs to be independent of the used theme.

Actual result

Environment

Paste the information here as shown by npm run check