Create consistant color-pallet (dark-mode friendly)

[SirLich]

Currently, we have colors defined in quite a few places:

• BButton
• The colors for our tags (beta, exp, guide)
• The color of our tip/warning/error modals
• Color of our badges (removed)

We need to look into a custom solution which provides two things:

• A css class (like blue, orange) that sets backround color
• A TS solution which returns css class as a switch-statement based on asked-for color. Should be used in :class

Both solutions need to return different colors depending on the theme.