.biz-course-play .video-player{width:100vw;height:100vh}.back-btn{position:fixed;top:calc(env(safe-area-inset-top, 0px) + 12px);left:12px;z-index:9999;width:36px;height:36px;display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-box-align:center;-webkit-align-items:center;-ms-flex-align:center;align-items:center;-webkit-box-pack:center;-webkit-justify-content:center;-ms-flex-pack:center;justify-content:center;border-radius:50%;background:rgba(0,0,0,.45);color:#fff;font-size:18px}