<!DOCTYPE html>
<meta charset="utf-8">
<link rel=stylesheet href="resources/backdrop-filter-backdrop-root.css">
<div class=container>
<div class=testcase>
<div style="opacity:0.9"></div>
<div class="box2" style="border-color: #021919; background: #00ffff;"></div>
</div>
<div class=testcase>
<div></div>
<div class="box2" style="background: #00ffff;"></div>
</div>
</div>
<style>
.box2 {
top:-50px;
left: 50px;
border: 1px solid black;
}
</style>