This is only a workaround.

I had already mode some modification Preston Scheuneman's Dark Static transparency style; player-width, alerts box, and many small items....This is a workout around made from an "in progress modification" that I was making before and while youtube "surprised" us with their new style, so ...yeah....

I'm waiting as well as everyone for an up-date of "YouTube - Dark Static, transparency".
Meanwhile, I'll try to do what I can to clean the obsolete code now.
This here is my style sheet that works in my firefox, it is the rough sheet that I work in.
So yeah, this is a quick fix.

Peace

below are the top and bottom of the whole page (screengrab)