Do you plan to make the top header configurable? I prefer to have it set to remaining minutes in chapter instead of page progress. But it's just a small thing I can adapt to, I roughly know how many pages I can read per minute.
Looking forward to a 5.18.x / 6.x compatible version
PS
The best thing about Kobalt is that it doesn't sometimes clip the last line of a page on my Clara BW
.