a {
    background-image: image-set(url(foo@1x.png) 1x, url(foo@2x.png) 2x);
}

h1 {
    background-image: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}

.class {
    background-image: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}

.class {
    border-image: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}

.class {
    mask: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}

.class {
    mask-image: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}

.class {
    list-style: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}

.class {
    list-style-image: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}

.class {
    content: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}

.broken {
    content: image-set('foo@1x.png' 1x, "foo@2x.png" 2x) "test";
}