Improve contrast of our Design

[emilk]

Currently our design has very low contrast between elements. Here is a screenshot from https://www.figma.com/file/3WX8yUqa8ECmhLwV6NIF3a/Rerun-Design-System?type=design&node-id=1252%3A15687&mode=design&t=Xc27rEOvAdS7F0XZ-1

The top element here has a different background color (barely):

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This looks great if you

• have a good screen
• have good eyes
• are in a dark room

However, if you are using a bad screen in a light room, the contrast between these background elements is way too low (the text is fine).
We either need to make the contrast higher, or add border strokes or similar.

Our current solution is to not follow the design guidelines.

This problem is exacerbated by not having a light mode you can switch to when you're in a brightly lit room (#3058)

[Wumpf]

Related to

• Hover outline contrast is too low #1839

[nikolausWest]

TBH, the screenshot above still has better contrast than our actual app:

[Wumpf]

not the bit where the context menu overlaps the background:
Actual:

Figma: