Using this email template as an example, you can see that there is text over a background image:
https://www.sendwithus.com/resources/templates/skyline
It is clear how to convert this template to a Mautic email theme where all the text is editable.
However, I have not been able to make the background image editable in the builder. Here is the relevant code:
<td background="https://www.filepicker.io/api/file/kmlo6MonRpWsVuuM47EG" bgcolor="#8b8284" valign="top" style="background: url(https://www.filepicker.io/api/file/kmlo6MonRpWsVuuM47EG) no-repeat center; background-color: #8b8284; background-position: center;">
<!--[if gte mso 9]>
<v:rect xmlns:v="urn:schemas-microsoft-com:vml" fill="true" stroke="false" style="mso-width-percent:1000;height:303px;">
<v:fill type="tile" src="https://www.filepicker.io/api/file/kmlo6MonRpWsVuuM47EG" color="#8b8284" />
<v:textbox inset="0,0,0,0">
<![endif]-->
As you can see, these types of background images are coded in the cells of a table. Is it possible then to have an editable background image in a Mautic email template?