.mt__44{ margin-top: -44px}

.img{ width:100%; min-height: 300px; float:left; text-align:center; position: relative}
.img img{ max-width: 100%}

.down_box{ width: 100%; height: 120px; float: left; position: fixed; left: 0; bottom: 0; background-image: linear-gradient(rgba(255,255,255,0),rgba(255,255,255,1) 50%); z-index: 1}
.down_box.pa{ position: absolute}
.down_box .btn{ width: 188px; line-height: 52px; float: left; background-color: #333; border-radius: 50px; font-size: 19px; color: #fff; text-align: center; position: absolute; top: 18px; left: 50%; margin-left: -94px}
.down_box .arrow{ width: 27px; height: 27px; float: left; background: url("../images/hero/app/1.png") no-repeat; background-size: 27px 27px; position: absolute; top: 77px; left: 50%; margin-left: -13px; animation: arrow 1s linear infinite}


@keyframes arrow{ 0%{ transform: translateY(0)} 50%{ transform: translateY(8px)} 100%{ transform: translateY(0px)}}