http://www.quirksmode.org/bugreports/archives/safari/index.html "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 http://amber.tangerinecs.com/examples/safari_form_bug.html Workaround is included Reported by: Amber Rhea."
This is a dupe of another bug, which i can't find, but has been solved, closing as worksforme.