Is there an easy way to theme Preformatted/CodePane in Markdown?

### Question
In my custom theme the font sizes in MarkDown generated Slides for preformatted Text are a lot smaller than other font sizes, because I had enlarged the latter.

### Background Info/Attempts

From reading the documentation, doing some experimenting and reading the code, I did not find an easy way to change the fontSize in the MarkDown preformatted elements.