Update colors.styl
Updated Stylus to `0.43` and tests for it
Merge branch 'pr/67'

* pr/67:
  Update colors.styl

Conflicts:
	lib/variables/colors.styl
Changed default text color to black
Added a way to configure border-alpha of pseudo-buttons, fixes #68
Added a way to center the content of simple inputs, fixes #66
Added examples of big promo-buttons
Fixed the difference in box-shadow for promo-buttons, fixes #65
v0.26.0