Improve contrast primary action buttons

[tijlleenders]

Is your feature request related to a problem? Please describe.
It's very annoying when you can't read something because there is not enough contrast.

Describe the solution you'd like
Adapt the theme colors for both dark and light themes so that contrast is according to good design guidelines.
Probably just re-use the technique for the breadcrumb :

Describe alternatives you've considered
None.

Additional context
This is how it looks now. Not very readable.