Yes, add a css style sheet with all your main default styles, text color, size, heading, links, body background of what their content area background will be. Call it cms_mystyle.css or whatever you want, save it into the HTMLEditor/custom folder, then add the link to it at the bottom of contents_insert_ContentValue1.js and the contents_update_ContentValue1.js
Thanks for the post, that's what i'm trying to do, but I'm not quite certain exactly what code to put when adding the link to the bottom of contents_insert_ContentValue1.js and the contents_update_ContentValue1.js
Could you be a little more specific, that'd be a great help.
Thanks
Kris