.btn-back{width:1rem;height:1rem;position:fixed;top:.3rem;left:.3rem;border-radius:50%;background:rgba(0,0,0,.5);line-height:1rem;font-size:.6rem;z-index:9999999999999;display:-webkit-box;display:-webkit-flex;display:flex;-webkit-box-pack:center;-webkit-justify-content:center;justify-content:center;-webkit-box-align:center;-webkit-align-items:center;align-items:center;opacity:.8}