嵌入视频自适应

.videoWrapper {
	position: relative;
	padding-bottom: 56.25%; /* 16:9 */
	height: 0;
}
.videoWrapper iframe,
.videoWrapper object,
.videoWrapper embed {
	position: absolute;
	top: 0;
	left: 0;
	width: 100%;
	height: 100%;
}

https://css-tricks.com/NetMag/FluidWidthVideo/Article-FluidWidthVideo.php