Color iteration in Stylus? Nope.

colors.styl

// Only one of the strings in the list of colors gets interpolated, thanks
// to Stylus converting the color keywords to hex values.
// Thanks, Stylus!

li
  for color in red pink orange yellow green blue purple brown black shit
    &.{color}
      background: color
      
// What I had to do instead to make it work. Note that simply wrapping the
// values in quotes and leaving them inline in the for loop does not work.

li
  classes = "red", "pink", "orange", "yellow", "green", "blue", "purple", "brown", "black"
  for color in classes
    &.{color}
      background: unquote(color)