.wp-block-video video{
    max-width: 100%;
}
.wp-block-audio.aligncenter{
    text-align: center;
}
.wp-block-audio figcaption{
    margin-top: 8px;
    margin-bottom: 0;    
}
.wp-block-audio.aligncenter,
.wp-block-pullquote.aligncenter {
    text-align: center;
}