Nicole:
Thanks for the clarification! I wasn't aware that Marketo strips out divs in final processing. I just checked with a test email, though, and the <div> with styling was not filtered out in the final result—maybe a result of breaking the normal Marketo regex filtering by adding a "style" property?
Dan:
Just replicated your problem. It's interesting that the default font is Verdana 10px, and I looked around and haven't found a place to change the default font.
The problem is still the WYSIWYG editor for emails, and Marketo's isn't up to par. I don't think there's a real answer to your problem (bug?), only to work around it. For the cleanest code with fewest headaches, it's probably easier to edit your email's copy in another program and copy+paste the pristine version at the end. Obviously not an ideal solution, but I haven't found an ideal WYSIWYG in... well, ever.
Also very interesting point on only Chrome... now that throws in another mind-boggling piece, since how would that affect the server-side filtering?
Best,
Edward Unthank
SEO/Web Specialist
Yesler