clipped from: www.noscope.com   

Showing CSS to IE only (The Underscore Hack)

It allows you to show CSS to Internet Explorer only, omitting Mozilla, Safari and Opera.

  • It allows you to write conditional CSS directly in your stylesheet file, and doesn’t require inline styles
  • It works for IE 5.0, 5.5 and 6.0
  • It’s a hack
  • It’s very simple to work with.
    • body {
    background: green; /* show to Mozilla/Safari/Opera */
    _background: red; /* show to IE */
}

    Cons

  • The CSS won’t validate
  • The hack won’t work for IE5/Mac. For this platform, I recommend the IE5/Mac Band Pass Filter hack