.wp-block-embed-youtube {
overflow: hidden;
position: relative;
max-width: 100%;
height: auto;
padding-bottom: 56.25%;
}
.wp-block-embed-youtube iframe,
.wp-block-embed-youtube object,
.wp-block-embed-youtube embed {
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
}