foo {
  c0: transparentize(rgba(0,0,0,0.0), 0.1);
  c1: transparentize(rgba(0,0,0,0.1), 0.1);
  c2: transparentize(rgba(0,0,0,0.2), 0.1);
  c3: transparentize(rgba(0,0,0,0.3), 0.1);
  c4: transparentize(rgba(0,0,0,0.4), 0.1);
  c5: transparentize(rgba(0,0,0,0.5), 0.1);
  c6: transparentize(rgba(0,0,0,0.6), 0.1);
  c7: transparentize(rgba(0,0,0,0.7), 0.1);
  c8: transparentize(rgba(0,0,0,0.8), 0.1);
  c9: transparentize(rgba(0,0,0,0.9), 0.1);
  c10: transparentize(rgba(0,0,0,1), 0.1);
}