Very nice reader. There are a few things that are bugging me though (firefox 64.0 x32):
I have selected for it to show only unread messages, but when I mark an entry as read, it will not disappear until I reload the feed, folder or whatever. Is that intentional?
In the 5th view at least, clicking an article text will expand it, but clicking it again won't make it return to its original state. So depending on the feed I'm stuck with giant images. (e.g. http://www.computerbase.de/rss/news.xml)
Also, having a way to inject custom css and js would be nice.