FR: possible to change default font of line editing overlay?

Currently, the <input type="text"> in the line editing overlay window uses a variable-width, sans-serif font for editors to transcribe the line being displayed above. This has the, sometimes problematic, disadvantage of not being able to see the difference between an uppercase i and a lowercase L. See this screenshot for an example containing both:

Is there a chance we could get a monospace font such as Courier New, or at least a serif font such as Times New Roman in that input field? (In our local installation I've changed the CSS as a stopgap measure, but that's less than ideal of course as it breaks the code which determines the font size dynamically.)