// Responsive Video using CSS only .video { height: 0; overflow: hidden; padding-top: 35px; padding-bottom: 56.25%; // 56.25% = 16x9 position: relative; &--full { padding-bottom: 75%; // 75% = 4x3 } iframe { height: 100%; left: 0; position: absolute; top: 0; width: 100%; } }