Like user 36c61a, I've also been using Owl for over a year now, and I really like it.
ButI I have the same problem as him/her. Settings are not implemented properly, often Owl will not use classic theme even though it is activated, it still inverts colours on videos on certain sites and the Owl icon in the url bar disappears on some sites (like reddit, youtube, etc.)
This extension always had frequent updates, but in the last months nothing. A new update with some fixes would be great! Best regards