You can try the following:
Template
<div class="background-layer {{Tags}}"></div>
Note: It does not matter where this <div>
element is placed within the template.
Styling
.background-layer {
position: fixed;
top: 0;
right: 0;
bottom: 0;
left: 0;
z-index: -1;
}
.beginner {
background-color: lightblue;
}
.intermediate {
background-color: lightcoral;
}
.advanced {
background-color: lightgreen;
}