html,body{
    width: 100%;
    height: 100%;
}
.download{
    margin: auto;
    max-width: 1000px;
    width: 100%;
    height: 100%;
    overflow-y: auto;
    background-color: #c21318;
    position: relative;
    max-width: 640px;
}
.download .content{
    width: 100%;
    position: relative;
}
.download .content .download_btn{
    width: 100%;
    background-color: rgba(0, 0, 0, 0);
    position: absolute;
    bottom: 9%;
    left: 0%;
    display: flex;
    justify-content: space-around;
    padding: 0 5%;
	max-height: 55px;
}
.download .content .download_btn img{
    width: 50%;
}
.download .mask{
    position: absolute;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.6);
    top: 0;
    left: 0;
    display: none;
}
.download .mask .img{
    position: absolute;
    right: 5%;
    top: 2%;
}

/*如果是禁用长按选择文字功能，用css*/  
* {  
    -webkit-touch-callout:none;  
    -webkit-user-select:none;  
    -khtml-user-select:none;  
    -moz-user-select:none;  
    -ms-user-select:none;  
    user-select:none;  
}