If you want to apply a background image and/or color and have it show behind the header and any other blocks, start with this…
<style>
body {
background-color: #ff0000;
background-image: url("https://example.com/your-image.png");
background-repeat: no-repeat;
background-size: cover;
background-attachment: fixed;
}
.spr-content-root,
.spr-horizontal-header,
.spr-horizontal-header header,
div[category="Hero"],
div[category="Pricing"] {
background-color: transparent !important;
}
</style>
the category lines will remove the background from all blocks of that type.