The Mega-Theme email template takes a banner image. To input/change your email template's banner image, simply go to your nation's primary website's* Site settings → Header image and upload your image.
*Find your nation's primary website by using your nation's top blue bar menu to go to Settings → Primary website.
Email Banner Image Guidelines
The image should be:
- rectangular (like a 4:3 or 4:2 ratio)
- .jpg or .png file type
- less than 400kb in size.
We usually create these by having a background image, a light overlay on top of the background image, and a logo on top of that. The overlay is appropriately colored and has the minimum opacity necessary to give the logo enough contrast.