The IE5/Mac Band Pass Filter

A comment with a backslash in it, exploiting a parser bug to serve CSS to exactly one browser on one operating system.

In 2026: Dead in the most complete way possible: the browser it targeted is gone, and every current parser reads the hidden block as an ordinary comment, so the rules inside reach nobody at all. A filter with nothing left to pass.

Where it came from: Tantek Celik's IE5/Mac band pass filter, published on tantek.com, 2000. Wikipedia ↗

<style>
p { color: black; }

/* Everything between these two comment tricks was visible
   ONLY to Internet Explorer 5 on the Macintosh */
/*\*//*/
p { color: red; font-weight: bold; }
/**/
</style>

<p>If this text is red, you are reading it on IE5 for Mac. It is not red.</p>