Improve option buttons for better visibility

[ofr1tz]

Is your feature request related to a problem? Please describe.
Currently, the option buttons in projects of type Validate and Compare are not always very visible or readable. This is particularly the case with Validate projects that can have configurable options with custom colors. See #42

Describe the solution you'd like
Buttons that are clearly visible, regardless of the color value, text or icon of the option.