property stacking

[tomhodgins]

This one really surprised me - it did it with color, background, lots of things!

html {
  background: red;
}
html {
  background: orange;
}
html {
  background: yellow;
}
html {
  background: green;
}
html {
  background: blue;
}
html {
  background: indigo;
}
html {
  background: violet;
}

correct minification

html{background:violet}

• redundant properties can be eliminated

CSSnano output

html{background:red;background:orange;background:#ff0;background:green;background:blue;background:indigo;background:violet}

• keeps previously declared background properties even though it can predict they won't apply