[FEATURE] Color custom / OLED dark

Hi! Currently, in the settings, we are allowed to create a custom theme. It's great, but I wanted to know if it was possible to create TWO custom themes : one for light mode, one for dark mode.

If I make this proposition, it's because I think an OLED Dark theme is missing in the settings (so simply add a switch button with "OLED Dark" can also be a solution).

Thank you!
