composited-iframe-hidden-subframe.html

<!DOCTYPE html>
<style>
.animatedBackground {
    width: 70px;
    height: 80px;
    position: absolute;
    background: url("./square-blue-100x100.png") no-repeat 0 0 transparent;
    animation: anim 4s steps(6) infinite;
}

.transformedItem {
    transform: translate3d(42px, 43px, 0);
    width: 40px;
    height: 50px;
    background-color: green;
}

@keyframes anim {
    100% {
        background-position: 9px 10px
    }
}
</style>
<div class="animatedBackground"></div>
<div class="transformedItem"></div>

chromium/third_party/blink/web_tests/compositing/resources/composited-iframe-hidden-subframe.html