.fluidMedia { position: relative; padding-bottom: 56.25%; /* proportion value to aspect ratio 16:9 (9 / 16 = 0.5625 or 56.25%) */ padding-top: 30px; height: 0; overflow: hidden; } 
.fluidMedia iframe { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }