I think I ran into a similar problem before and here is my workaround.
In the “additional head” of the email template, I’ve added these lines of code:
<style type="text/css" data-hse-inline-css="true">
#contentCell {
/* adjusts the color of the body wrapper */
}
#contentTableInner {
/* adjusts the color of the body */
}
#backgroundTable {
/* adjusts the color of the page, minus the header and footer */
}
#headerTable {
/* adjusts the color of the header containing address book */
}
#footerTable {
/* adjusts the color of the subscription links section */
background-color: #dedede;
}
body {
/* background-color: whatever you want */
}
</style>
And in whichever part of the email I’m targetting, I add the necessary background-color code.
background-color: #123123;
Hopefully that helps!