CSS Stylesheet Editor

The CSS Stylesheet Editor provides an easy method for creating and modifying CSS stylesheets for use with your HTML documents, without the need for knowledge of the CSS syntax. It provides intuitive fields for all of the CSS properties you're ever likely to need.

TopStyle Lite

This is a well-known Windows CSS editor that can also edit HTML code. The editor's speciality is that it allows you to create Cascading Style Sheets in a fairly simple manner - you can select the features you want from a side panel of the editor and it will generate the corresponding style sheet (you still need some CSS knowledge though - this is not a WYSIWYG editor). You can also edit HTML code with the editor. The Lite version, which is free, only allows you to create inline Cascading Style Sheets. The Pro version (not free) allows you to create external style sheets and includes built-in validators that checks your style sheets and HTML documents for correctness (among other features).

Webniac

Webniac is a text editor for web page development. It has syntax highlighting for HTML, CSS, Java, JavaScript, VBScript, PHP, SQL, Perl and XML. It includes some JavaScripts which you can use on your site, a CSS generator, facilities for constructing tables, etc.

Bluefish

From the announcement by one of their development team: "Bluefish is a programmer's HTML editor, designed to save the experienced webmaster some keystrokes. It features a multiple file editor, multiple toolbars, custom menus, image and thumbnail dialogs, open from the web, CSS dialogs, PHP, SSI and RXML support, HTML validation and lots of wizards." I've seen a lot of good things said about this editor by other webmasters. Bluefish runs on Linux, FreeBSD, Solaris, Tru64/Alpha, NetBSD, OpenBSD, HP-UX and Mac OSX.