Thanks for your suggestions, jackie_w—I made some changes to the rules that you referenced, and I realized I may not have been clear about what I'm trying to change (or I'm doing something wrong!)
Editing the css for #message appears to change the text used in the overlay status bar (which alternates between showing the time, the percetage read, and the book title). I'm actually trying to change the Book Title that shows at the top of the epub/kepub page when the overlay is not active (Pocket articles as well, assuming those are controlled by the same styling).
So far I've just been using trial and error, changing css rules, restarting my kobo and seeing what's changed. Is there an easier way to go about this, or is there a stylesheet reference that I can find on the forum? I've been using pipcat's css extractor to edit the nickel file:
https://www.mobileread.com/forums/sh...9&postcount=15.