how do you get fckeditor to render the CSS?

I'm just starting out here, but confused by something.

fckstyles.xml defines a "Computer Code" using the code tag. Ok, so I added a CSS definition (border, colors, etc...) for the code tag in editor/css/fck_editorarea.css and that doesn't apply the style. Also tried it in editor/skins/default/fck_editor.css

Is there something I'm missing here - is it supposed to render it based on the CSS?

Thx!