.intrinsic-container {
 position: relative;
 height: 0;
 overflow: hidden;
}
 
/* 16x9 Aspect Ratio */
.intrinsic-container-16x9 {
 padding-bottom: 56.25%;
}
 
/* 4x3 Aspect Ratio */
.intrinsic-container-4x3 {
 padding-bottom: 75%;
}
 
.intrinsic-container iframe {
 position: absolute;
 top:0;
 left: 0;
 width: 100%;
 height: 100%;
}