Adjust the orange background color to improve readability

[RVA2869]

The feature

Discussed on #348

Why?

Improved readability for web accessibility.

Examples and inspiration

[Abbe98]

Screenshots:

[RVA2869]

I was just thinking about this issue... Wouldn't it be better to have a high-contrast mode?
Because the dark orange doesn't match so well with the blue. (Just a thought)

[Abbe98]

That idea crossed my mind too, I think we should strive towards having better defaults but both the blue and orange would need to be updated and it would be a lot of work(CSS, icons, branding repo, presentation templates, etc). High-contrast mode is more bang for the buck.