I do all my coding, accept css, in HTML-Kit. A superb editor with a host of user created plug-ins. I could do the css as well, in fact I sometimes do quick tweaks this way but my preference is to use TopStyle. TopStyle has a 'Lite', free version as well as the paid for version.

TopStyle from http://www.newsgator.com/

HTML-Kit from http://www.chami.com/html-kit/