Usability suggestion: CSS option for coloring UI elements

[ghost]

Would help themes developer much if they would be able to change UI color or button color with the help of CSS. Vivaldi has that too, in fact you can with the help of CSS locate almost every single UI element where you want. Would be enhancing also quite a lot the UI of Brave.

[alexwykoff]

Closing due to:

1. No activity in 2 or less months.
2. Appears to be low impact.
3. No milestone assigned.

[bsclifton]

Just a note for folks reading this: there is a new about:styles page being worked on by @jkup which intends to show all the UI elements in one place 😄 This will help a ton when we get to proper theming

[luixxiul]

Closing in favor of #10967