I would like to start with a reminder: MS-Outlook does not render background images therefore <style>@media print{ #_t { background-image is not going to work regardless the way the email is defined. It is a known and documented limitation
http://www.campaignmonitor.com/css/CSS are valuable for landing pages. They define font styles, colours and other properties once and then just referenced when needed.
Emails need the styles defined for each element, such as
<td width="1" valign="top" bgcolor="#A8A8A8" style="border-collapse: collapse;"><img src="http://example.com/images/spacer2.gif" width="1" height="40" border="0" style="border: 0; display: block;"></td>
That sort of defintion is repeated for every element.