- Use web approx colors with postfix
-colorat the end, eg $black-10-color - rgba color should be name with the color name and alpha:
[color-name]-[alpha]-color, eg $thunder-90-color - Find colors tool http://chir.ag/projects/name-that-color/
-color at the end, eg $black-10-color[color-name]-[alpha]-color, eg $thunder-90-color