CSS border-radius implementation for YouTube iframe embed

demo.html

<style>
.div-round {
	overflow: hidden;
	position: relative;
	z-index: 10;
	-webkit-border-radius: 20px;
	border-radius: 20px;
}

.div-round::before {
	display: block;
	content: "";
}

.iframe-round {
	position: absolute;
	top: 0;
	left: 0;
	right: 0;
	bottom: 0;
	z-index: 10;
	width: 100%;
	height: 100%;
	border: 0;
	-webkit-border-radius: 20px;
	border-radius: 20px;
}
</style>

<div class="div-round" style="width: 640px; height: 360px;">
    <iframe class="iframe-round" allow="autoplay; encrypted-media; fullscreen" src="https://www.youtube.com/embed/Xjs6fnpPWy4?modestbranding=1&autoplay=0"></iframe>
</div>

so good