div.vimeo_player,
div.youtube_player
{
    margin-left: auto;
    margin-right: auto;
    max-width: 100%;
}

.wp-embed-responsive .wp-has-aspect-ratio div.vimeo_player,
.wp-embed-responsive .wp-has-aspect-ratio div.youtube_player {
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    height: 100%;
    width: 100%;
}