How to change default editor font

I'm having trouble setting the default editor font to my desired font. I am using the config option "bodyClass":

CKEDITOR.config.bodyClass = 'richTextEdit';

And my css definition is:

.richTextEdit {
font-family: Serif;
}

But the font is still showing up as Sans-Serif/Arial. I've tried using !important and making the style more specific. It seems that for a second as the editor loads, the font is correct, but when fully loaded it reverts back to the Sans-Serif style. I'm using the Kama skin. Am I using the right config property?

Thanks for any help.