Yes it is a bummer, I have spent the last 10-11 days without an internet connection and trying to repair it. If you get this reply, it is my first internet connection in 11 days.
My display is 1366 x 768 and it fits fine. It would help me to get each of your display sizes. Any input will help me solve the issues.
I have created themes that should have worked but for some reason they appeared to be cropped by Firefox and only ending up using one half of both the top and right side of my actual theme.
My internet issues are not fully fixed yet.