Steps to replicate the issue (include links if applicable):
- View a page with syntaxhighlighting such as https://en.wikipedia.org/wiki/Module:Documentation
- Observe the first code block
What happens?: The <pre> with its border stops at the content floating right. The surrounding <div> does not.
What should have happened instead?: The background should stop.
Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):
Other information (browser name/version, screenshots, etc.):
This is due to the various background CSS currently targeting div.mw-highlight. There's presently two blocks of it that will need to be removed, one of which is created by updateCSS.php. (Maybe one after T365774.)
