We offer an online web builder / CMS. It is aimed at web designers/developers rather than end-users, so has a lot of support for best practice css-based layout.

The CMS part includes page content editors, that obviously are aimed at the end user (i.e. our customer's customer).

Increasingly, the challenge is that designers are applying a lot of text and layout stying based upon a cascade of elements. The page content editor is editing HTML, out of the context of the website page where it will be displayed, and this means that what the user of the editor sees is not what they get on the website.

I'm wondering what experience people have had with other content editing tools. Is it now generally the case that 'WYSIWYG' tools do not accurately represent how the site will look when complex CSS rules are applied, or are there tools that do a comprehensive job of always displaying editable content with ALL the styles that it should inherit once placed in context in the target webpage?