.embed-responsive-16by13{aspect-ratio:16/13}.embed-responsive-16by13::before{padding-top:81.25%}.embed-responsive-4by3{aspect-ratio:4/3}.embed-responsive-4by3::before{padding-top:75.00%}.embed-responsive-48by31{aspect-ratio:48/31}.embed-responsive-48by31::before{padding-top:64.58%}