YUI toolbar icons stacked instead of inline - why?

Hi,

I'm using the WYSIWYG module with YUI on a default drupal installation with no additional modules/plugins/whatever other than the default. Everything is of the latest version. And yet, the YUI button toolbar icons are stacked, not inline. See this image:
http://bayimg.com/image/caaldaacl.jpg

Am I missing something here or is this how it's supposed to look? I've tried editing the editor.css file to remove the appropriate parts, with mixed results, and I'm worried that it won't display properly in IE and other Windows browsers.

This behaviour should be replicable for anyone, I've tried it in different browsers (Safari, Webkit nightly, FF, Camino etc).

Any input would be great!

Thanks.