Youtube inscreen control button background color code edit
Recently I chaged firefox font color and (font)background color; font color near white, (font)background color near black. From that time Youtube in_screen control button's (play/pause/sound/setting/full screen) background color changed to near white (default translucent) so the buttons became barely distinguishable.
I changed font/background color to the original, installed themes and addons but failed to set the buttons back to the original color.
Slidebar color changed to (font)background color.
I have eyes problem and some internet sites don't allow the dark mode, So I had to try browser color code editing for my eyes.
Could someone please tell me how to reverse the change or change the button's background color translucent?