.mce-content-body img,
.article-detail .article-detail__content img {
    max-width: 100%;
    height: auto;
    display: block;
}

.youtube-b {
    display: block;
    padding-top: 56.25%;
    position: relative;
    width: 100%;
    height: 0;
}

.youtube-b .mce-object-iframe,
.youtube-b iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}