.ratio-16-9,
.ratio-16-10,
.ratio-square {
    display: block;
    position: relative;
    width: 100%;
    height: 0;
}

.ratio-16-9 {
    padding-top: 56.25%; /* This is your aspect-ratio */
}

.ratio-16-10 {
    padding-top: 62.5%; /* This is your aspect-ratio */
}

.ratio-square {
    padding-top: 100%; /* This is your aspect-ratio */
}

.ratio-inner {
    display: block;
    position: absolute;

    left: 0;
    top: 0;
    right: 0;
    bottom: 0;

    width: 100%;
    height: 100%;
}