5.5+ behave like IE7 or Firefox

5.5+ behave like IE7 or Firefox

IE7 loads and parses all style sheets into a form that Explorer can understand. You can then use most CSS2/CSS3 selectors without having to resort to CSS hacks.

The lightweight script is a single-line inclusion in your HTML/XML document. No alteration of your original markup is necessary. Neither do you have to alter your CSS.

http://dean.edwards.name/IE7/

"By plugging in this script library you can have IE 5.5+ behave like IE7 or Firefox, go away CSS hacks!. Apparently this script even had attention from the MS IE7 dev. team."
- Via: Ramakrishnan Annaswamy/CD mail list.