Mimicking the built in email template design/layout

Mimicking the built in email template design/layout

Hello,

I am creating new email templates, but I would like to mimic the look of the built in ones that use a gray background and then a white inner box that the text is on (screenshot below). It looks like it is using two tables, one inside another, but I can't figure out how to make the outer table's background gray. I feel like I'm probably just missing something easy.



Thanks!