[FireAtlas] Better contrast on initial buttons

[spydon]

What could be improved

It's pretty bad contrast between the text and the button background on the "Open atlas" and "New atlas" buttons.

Why should this be improved

So that visually impaired (and myself :joy:) can see what it says on the buttons.

Risks

No response

More information

No response

Other

• [ ] Are you interested in working on a PR for this?