Cleanup colors

[nichtich]

• [x] remove hard-coded color values from all components
• [x] remove colors which are not used
• [x] possibly replace colors which are only used once with another color
• [x] derive all colors from a set of base colors (color-primary, color-select, color-action-...)

[stefandesu]

• [x] align color scheme to coli-conc website