.floor-box{ 44px; border: 1px solid #ccc; position: fixed; left: 50%; z-index: 1000}
漂浮距离,距中间50%
.floor-box{ 44px; border: 1px solid #ccc; position: fixed; left: 50%; margin-left: 620px; bottom: 30px; background: #fff; z-index: 1000}
漂浮距离:距离中间50%,在减去620px