CSS Not ([hacks])
http://www.digital-web.com/articles/CSS_not_hacks/

Suda, Brian
Digital Web Magazine
2008

Abstract:

As any web developer worth his salt will know, browsers can differ in their interpretation of CSS rules and properties. One way of coping with this headache is to use various hacks; they might (in some cases) be invalid CSS, but they force browsers to read only certain parts of your CSS and render your page or web site as close to how you intended as possible. CSS hacks are one of the common ways to send specific instructions to different browsers, be it to solve min-width issues or box model interpretations.