More improvements/fixes of Nord theme

[math-GH]

Ref #5689
Ref #5719

Some more improvements of Nord theme

[math-GH]

Before:

1. in mobile view: the favicons had a grey background on the right hand side
2. the unread counter was not perfect positioned
   

After:

[math-GH]

Before:
the color of the table border where missed, so it was just plain white.

After:
it has a dark color

[Alkarex]

How much till its ready, more or less? I think we are ready for the release of 1.22.1

[math-GH]

let's merge it here :)