VT100 for life!

But more seriously, I should have been more specific. Having the second file open in a split pain isn't that big of a deal, but having to navigate and find the right selectors can be. If class names are used well then it's pretty easy to find those, but my experience with that is riddled with inconsistency when I'm not the one who wrote it.

On that note, it's also much easier to review CSS changes in pull requests when they are right in line with the file. Otherwise I have to do the same lookup to find the corresponding HTML, and reason about whether the selector could potentially be grabbing things that aren't obvious, etc.