背景画像の縦横比率を維持 http://blog.looseknot.jp/sample_html/background-image-size.html
.detail_interview-mv{ box-sizing: border-box; background: url(https://unsplash.it/1280/522) center center no-repeat; background-size: cover; width: 100%; height: 522px; padding-top: 40.7%; }