An odd one today at work, a site had the following:
<link rel="stylesheet" href="styles.css" />
<link rel="stylesheet" href="print.css" media="print" />
What was puzzling was that when you printed the page from Firefox, none of the styles from styles.css were being applied. I for one had assumed that it would be inherited.
It turns out that it's not clear what the default media value for the link element is. The HTML4 spec says: