Works in Firefox. Nits:

• Does not show br (line break) or img (image) tags. If you know how to apply CSS to br or img elements, please tell me.
• The cursor goes invisible when it is adjacent to an end tag (the cursor is still there, you just can't see it).

Does not work in Chrome. I think this is because the CSS rules select elements http://forum.userstyles.org/discussion/15032/how-to-apply-css-to-content-within-an-iframe/.

Change history (yyyy-mm-dd)

2012-08-08

Added a @-moz-document wrapper to restrict this user style to Confluence rich text editor pages.

2012-08-09

Adjusted regexp in @-moz-document wrapper to include create action, not just edit.