Dark mode

[andrija-naglic]

First of all, thank you for this great extension @tomimick ! It's a nice tool I use fairly often.

How about a dark mode? :) I'm willing to invest some time in creating a PR, but could use some help in form of directions - where would be a best way to start and what all should be done to achieve this?

I would love to see this as a checkbox in the Options. I already have some custom CSS saved there, but that's far from what it could be. As I understand, highlight.js library is already prepared for it.

[tomimick]

Hi there. If you have interest in creating a dark-mode, I can certainly release it.

I think the work includes these tasks:

• a new checkmark "Dark mode" in the options
• new file maintab-dark.css that provides the dark look for the main UI, is appended after maintab.css perhaps
• new file darkmode.css that is a replacement for current googlecode.css