In Safari, if you have a form that's inside a div with the clearfix (read about it here) class applied, the form will not show up on the page unless you specifically apply display: block to the containing div.

Test page Workaround is included
Reported by: Amber Rhea.

Let's say that you have an element with an id of id. This element can have either of two different classes, classOne or classTwo. (Either you're swapping the className in script, or it can have different classes on different pages.)

Your CSS might look like this:

#id.classOne { some styles }
#id.classTwo { some different styles }

In MSIE 6, the #id.classTwo style will never be applied - unless it is put in a separate style tag or style sheet.

Test page Workaround is included
Reported by: Isaac Z. Schlueter.