:before
и ему задается z-index: -1
, либо h1 { ... position: relative; z-index: 100; ... }
.h1:before {
content: "";
position: absolute;
z-index: -1;
top: -3rem;
left: -50%;
width: 30rem;
height: 11rem;
background-image: url(http://danielmall.com/articles/svg-workflow-for-designers/svg.svg);
background-size: contain;
background-repeat: no-repeat;
}