@beeters Add-on author here. This is the first time that I got an email notification from this Opera forum (which I didn't even heard of...) so that's why I missed the earlier comment.
@darkboft Regarding the earlier comment:
- Currently it should be possible to switch theme from add-on options.
- That sounds reasonable.
- Triple click on any of the hovercard there will be a form which let you provide an access token which enables private repos and actions like star/unstar/follow/unfollow. (The form also appears when you reach GitHub API's limitation for unauthorized requests. As the add-on works on GitHub enterprise so that a user may need to provide multiple tokens, I didn't put this into options to make it complicated. But I admit this is a little hard to find.) This currently can be found at the GitHub repo for the add-on (https://github.com/Justineo/github-hovercard#faq).
I didn't have much spare time to put into this add-on for quite a long time, and GitHub's UI is changing very frequently and they had been adopting atomic CSS (instead of giving elements classnames according to semantics), which makes it extremely hard to identify proper hovercard targets. To be honestly I'm a little surprised that it can still work.