Hello
To amend you can add the following to the Custom CSS field of your templates parameters (Extensions -> Templates -> [YourTemplateStyle] -> Custom CSS)....
Replace # with the URL to your image...
#container_header, #container_hornav {
background-color: transparent;
}
#body_panel {
background-image: url('#');
background-size: 100%;
background-repeat: no-repeat;
background-position-y: 0;
}
.is-sticky #container_hornav {
background-color: #fff !important;
background-image: none;
}
CiarĂ¡n