Hi

You can install a colour theme of your choosing from:

https://addons.mozilla.org

I hope that this helps.

I don't see the old theme there either, I hate every single new theme out there, too dark too light too distracting, I want the old theme back!!!

Hi , There's a Firefox theme on the addons site called Photon Colors, which I found helps a lot.

Go to https://addons.mozilla.org/firefox/addon/photon-colors/ and click on Install Theme.

I also do not like the new appearance - too much white space and my shortcut icons are much too small. You should have given the option to keep the old 'classic" theme. I liked the former look of the tabs with a clear definition (vertical line/rounded corners) between them.