<div class="constant-width-to-height-ratio"></div> .constant-width-to-height-ratio {
background: #9C27B0;
width: 50%;
} .constant-width-to-height-ratio:before {
content: '';
padding-top: 100%;
float: left;
} .constant-width-to-height-ratio:after {
content: '';
display: block;
clear: both;
}
