mix(rgba(51, 255, 51, 0.90), #f00) => rgba(163, 114, 22, 0.95) alpha(rgba(51, 255, 51, 0.75)) => 0.75 opacity(rgba(51, 255, 51, 0.75)) => 0.75 opacify(rgba(51, 255, 51, 0.75), 0.1) => rgba(51, 255, 51, 0.85) fade-in(rgba(51, 255, 51, 0.75), 0.1) => rgba(51, 255, 51, 0.85) transparentize(rgba(51, 255, 51, 0.75), 0.1) => rgba(51, 255, 51, 0.65) fade-out(rgba(51, 255, 51, 0.75), 0.1) => rgba(51, 255, 51, 0.65) Sass 2.4 color functions with alpha support! http://nex-3.com/posts/89-powerful-color-manipulation-with-sass