You. Will. Never. Go. Back. I mean...variables? Do you never have the same width in two places? That is so simple and so huge. Want to make your shade of green

You. Will. Never. Go. Back. I mean...variables? Do you never have the same width in two places? That is so simple and so huge. Want to make your shade of green 5% darker? Don't look up a new hexadecimal, just say darken(green,5%). Make a button "class" where the only input is a color, and it automatically generates a cross-browser rounded-corner button with a slight gradient to 10% darker color, 20% darker border, with 20% lighter inset box shadow. Really. You will not go back.