Currently it is possible to define CSS files and its content headers in the atlassian-plugin.xml descriptor. What is not possible is setting media type for these files.

This prevents theme and plugin developers from taking full advantage of the new way Confluence handles printing (as of 2.8). Mainly, if a plugin output should not be visible in the printable output, achieving this without hacking the theme templates is not possible.

It would be great if an additional property was supported in the descriptor, something like:

<resource type="download" name="style.css" location="com/example/plugin/style.css">
   <property key="content-type" value="text/css"/>
   <property key="css-media" value="print"/>
</resource>