.embed-responsive-16by9{aspect-ratio:16/9}.embed-responsive-16by9::before{padding-top:56.25%}.embed-responsive-4by3{aspect-ratio:4/3}.embed-responsive-4by3::before{padding-top:75.00%}.embed-responsive-48by25{aspect-ratio:48/25}.embed-responsive-48by25::before{padding-top:52.08%}