Werhooooo! I think I’ve squashed that bug!!!
Can you please check in your Edge Browser too?.
All I did was add this CSS:
.site-header {position:inherit; line-height:normal;}
So your line-height code was indeed part of the solution in the end, thanks Tom.
To make the CSS work specifically for Edge I’ve also changed it to this:
/* Fixes hover lines issue in Microsoft Edge */
:-ms-lang(x), _:-webkit-full-screen,.site-header {position:inherit; line-height:normal;}I don’t believe my CSS would cause any other issues going forward?.
Also, I have found another GP site (not one of mine) where the issue is appearing.
This confirms the bug is not related to just my website, which is a relief to me as I thought I had some kind of corrupted install/server issue.
Hope this helps someone in the future.