Custom font size is overridden in markdown pre blocks

* **Browser**: Google Chrome * **Operating System**: Windows 11 * **Link to page with the issue**: https://github.com/rails/rails/pull/56107 * **Screenshot**: <img width="3839" height="1951" alt="Image" src="https://github.com/user-attachments/assets/a130205e-0def-453c-967e-c0c263a04859" /> I'm using just github-custom-fonts.user.css with Stylus. I have the custom font set to SF Mono and the size set to 13px instead of the default of 12px. It works in the Files changed view, but it doesn't work anywhere in the `<pre>` where there's a code block in a PR comment. It also doesn't work in code blocks in READMEs, such as those [here](https://github.com/rails/rails). It looks like the issue is there's a selector setting `font-size: 85%` for `.markdown-body .highlight pre, .markdown-body pre`. I think if these classes are added to the CSS selectors, it should fix the issue.