* Improve disabled styles for repo buttons
- Simplify disabled styling of label by matching for the disabled
attribute.
- Raise fomantic disabled opacity from .45 to .55 to for more contrast.
- Use CSS vars for basic button styles.
* restore clickability on label
* color tweaks and remove arc-green style
* slightly reduce button size
* consolidate vars
* also cover active class
* slightly more distinct active class
* remove useless rule
silverwind