Robin Houghton — You can enter the following code snippet into the HTML source view of the Map Series builder to use a custom graphic in the header. The image already needs to be hosted on the web somewhere (you can’t use an image uploaded to your story for this).
background: url("[your-image-url") no-repeat center 62%/100% !important;
height: 110px !important;
Depending on the size of your image, you’ll probably need to play with the size %s (“62%/100%”) to get it to display where you want it.
Also some images don’t look great since there might be a drastic/abrupt transition to the tab bar. Depending on the theme and your image you might be able to use a linear gradient for the background color to blend into the tab bar, if needed.
For example, if your tab bar is black something like this might work…
background: linear-gradient(rgba(35, 35, 35, 0.15) 45%, rgba(35, 35, 35, 0.9) 80%, rgba(35, 35, 35, 1) 100%), url("[your-image-url.jpg") no-repeat center 62%/100% !important;}
Hope this helps!