If you are looking for a powerful HTML editor and previewer which you can use for good WYSIWYG HTML and CSS editing then Kompozer is the best free option for you. It is widely popular as a complete web authoring platform which includes web file management and easy WYSIWYG web page editing features which you might have seen in FrontPage, Adobe DreamWeaver and other programs.
Kompozer is user-friendly and is ideal for non-technical computer users who like creating professional looking web pages without any knowledge of HTML and web coding. You can know more of its features and options here on its Official Website. You can download it from here.