Harvey Morse Code Hack (css hack for ie7)

I have just accidentally discovered a hack css for Internet Ignorer 7 with the dot dash sequence needing to be identical to below...

body{
background:red; /* all "normal" browsers */
.background:green; /* ie <=6 and 7 */
_background:blue; /* ie <=6 only */
}

Enjoy my fellow web developers!

Cheers
Jon