Dark theme option

[DazzWh]

I've been using this a lot at night and the blinding white is almost my only gripe. Annoyingly the dark theme browser extension I use doesn't work nicely with the SVG stuff, so took to creating my own dark theme css.

Now I'm not a great UI designer, but I could polish it up by finishing the scheme and adding an option in the settings dropdown, then submit a PR if there's any interest in it getting used.

Looking at how the generated SVG colours are intergrated with the TS logic is why I'm not going to do it if no one wants it, as that looks like it'll be more work to get right than just replacing a css file 😄

[Mike Hadlow]

Thanks for raising this, and very pleased that you're finding GD useful. I think it would be a really nice option. If you do decide to do it, I'd like to see it as two separate PRs, the first to remove all hard coded colours from the TS code to CSS (in effect to make GD theme-able), and then the second to provide the dark theme.

[DazzWh]

Alright, sounds like a good way to tackle it. I'll chip away at it over the next month or so!