Dark mode

[stepan662]

Improve dark mode proposal
#997

[cyyynthia]

I know this issue mostly targets the webapp more than the website, but it may be worth including revisiting slightly the website dark theme as well which has very low contrast ratio in certain places.

The brand color really doesn't play nice with a dark background: 2.8 contrast ratio, while the Web Content Accessibility Guidelines require a minimum contrast ratio of 4.5, and suggest a contrast ratio of 7 for enhanced contrast.

[JanCizmar]

I know this issue mostly targets the webapp more than the website, but it may be worth including revisiting slightly the website dark theme as well which has very low contrast ratio in certain places.

It's now updated on the website!