margin: 0;
    width: 200px;
    height: 200px;
}
div { background: red; }
body {
    overflow: hidden;
    contain: paint;
}
:focus {
    outline: none;
}
</style>

<div></div>
<p tabindex=1 id=target>Test passes if there is no red.
<script>
window.onload = function() {
    document.getElementById("target").focus();
    setTimeout(() => {
        document.documentElement.className = "";
    }, 0);
}
</script>
