From an article at javascriptkit.com, that's applied for IE 7 and earlier versions:

if you add a non-alphanumeric character such as an asterisk ( * ) immediately before a property name, the property will be applied in IE and not in other browsers.

Also there's a hack for <= IE 8:

div { color: blue; /* All browsers */ color: purple\9; /* IE8 and earlier */ *color: pink; /* IE7 and earlier */ }

However that's not a good idea, they don't validate. You always feel free to work with Conditional comments for targeting specific versions of IE:

<!--[if lte IE 8]><link rel="stylesheet" href="ie-8.css"><![endif]--> <!--[if lte IE 7]><link rel="stylesheet" href="ie-7.css"><![endif]--> <!--[if lte IE 6]><link rel="stylesheet" href="ie-6.css"><![endif]-->

But for those wanna see the hack in real, please open up this page in the latest version of IE you have. Then go to developer mode by doing a F12 . In Emulation section ( ctrl + 8 ) change document mode to 7 and see what happens.