.video-container {
position: relative;
padding-bottom: 56.25%;
padding-top: 30px;
height: 0;
overflow: hidden;
}
.video-container iframe, .video-container object, .video-container embed {
position: absolute;
top: 0;left: 0;
width: 100%;
height: 100%;}
/*padding-bottom: 56.25%為影片高度與寬度的比例16:9計算得來，9除以16=0.5625換算高度比0.5625=56.25%
padding-top: 30px:用於修正的高度，可用25px或30px*/