www.htmlkit.com/
Standards-compliant full-featured editor for HTML, XHTML, XML, CSS and other common languages. 95% thumbs up on Download.com User Opinions. 4+ million overall downloads (1.8+ million through CNET/ZDNet). HTML Tidy and other plugins for creating clean HTML/XHTML pages.
(please note what's in quotes is from the respective website)
i've been using this editior for years --
-- and the price tag fits everyones budget FREE
Has tons of plugins
Over 440 free plugins are available for extending and customizing HTML-Kit to fit the way you work. Categories include ASP, ColdFusion, C#, iHTML, Java, JavaScript, JSP, Perl, PHP, Python, SQL and more.
aside from HTML Tidy as a plugin you can go onlinet from htmlkit to validate your html or css doc using w3c validator
Then you can install
TopStyle Lite as CSS editor
and your good to go 
www.newsgator.com/NGOLProduct.aspx?ProdI...pStyle&ProdView=lite
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open the css document in html kit -- hit preview -- (on the bottom toolbar) and
topstyle lite will open -- got to like that one 
i strongly recommend above mentioned programs -- and once you give them a go -- i'm sure you'll share this info 
enjoy
barb