.upload-tip{padding:0 10px;height:36px;line-height:36px;text-align:center;background:rgba(0,0,0,.75);box-shadow:0 2px 8px 0 rgba(38,114,255,.1);position:fixed;left:50%;top:50%;transform:translate(-50%,-50%);color:#fff;font-size:14px;border-radius:4px;transition:all .5s linear}