youtubeレスポンシブ対応

■css
.youtube-waku {
max-width: 850px;
margin-left: auto;
margin-right: auto;
}
.youtube {
position: relative;
width: 100%;
padding-top: 56.25%;
}
.youtube iframe {
position: absolute;
top: 0;
right: 0;
width: 100% !important;
height: 100% !important;
}