The !important Double Declaration

Old Internet Explorer ignored !important when the same property appeared twice, which turned a bug into a browser detector.

In 2026: Dead as a technique: every current browser honours !important, so both audiences now see red and the second declaration reaches nobody. It sits here as the purest specimen of the era's genre, CSS written for how browsers misbehaved rather than for what it said.

Where it came from: An Internet Explorer parser bug, catalogued on the CSS hack lists of the early 2000s. Wikipedia ↗

<style>
p.hack {
  color: red !important;   /* every correct browser stops here */
  color: blue;             /* IE4 and IE5 took this one instead */
}
</style>

<p class="hack">
  Red in a correct browser. Blue in old Internet Explorer.
  One property, two audiences, no scripting.
</p>