I'm using codehilite with the readthedocs theme. If I use the default config

markdown_extensions:
    - codehilite:

the code segments are highlighted, but they don't have a background:

If I add the linenums option to codehilite

markdown_extensions:
    - codehilite:
        linenums: True

then it does show a background, but the width varies with the size of the code block and there's no scrolling:

My question: is there any way to have codehilight highlighting with a colored background and scrolling? I couldn't find any documentation for what options codehilite allows. I would prefer not to use highlight.js.