.clearfix:after{clear:both;content:".";display:block;font-size:0;height:0;line-height:0;visibility:hidden}
.clearfix{clear:both;zoom:1}
.fl{float:left;display:inline;}
.fr{float:right;display:inline;}
.base-title-wrap{
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 1.4rem;
    z-index: 9;
}

.base-title-wrap .back-btn{
    position: absolute;
    bottom: .4rem;
    left: .6rem;
    display: inline-block;
    width: .666667rem /* 50/75 */;
    height: .666667rem /* 50/75 */;
    background: url(//image.zhihuishu.com/zhs/ablecommons/demo/201806/8579accc8e8b4aaa8084d4d0fc9c3921.png) no-repeat;
    background-size: 1.333333rem /* 100/75 */ 1.333333rem /* 100/75 */;
    text-indent: -9999px;
}
.base-title-wrap .share-btn,.base-title-wrap .service-btn{
    position: absolute;
    bottom: .4rem;
    right: .6rem;
    display: inline-block;
    width: .666667rem /* 50/75 */;
    height: .666667rem /* 50/75 */;
    background: url(//image.zhihuishu.com/zhs/ablecommons/demo/201806/8579accc8e8b4aaa8084d4d0fc9c3921.png) no-repeat;
    background-size: 1.333333rem /* 100/75 */ 1.333333rem /* 100/75 */;
    text-indent: -9999px;
    background-position: 0 -.666667rem /* 50/75 */;
}
.base-title-wrap .service-btn{
    background: url(//image.zhihuishu.com/zhs/ablecommons/demo/201806/f5fbddc557dc43ebac9a616c2be14806.png) no-repeat;
    background-size: 1.333333rem /* 100/75 */ .666667rem /* 50/75 */;
    background-position: 0 0;
}
.base-title-wrap.blur{
    background: #fff;
}
.base-title-wrap.blur .back-btn{
    background-position: -.666667rem /* 50/75 */ 0;
}
.base-title-wrap.blur .share-btn{
    background-position:  -.666667rem -.666667rem;
}
.base-title-wrap.blur .service-btn{
    background-position: -.666667rem /* 50/75 */ 0;
}
.base-title-wrap.blur .title-content{
    color: #333;
}
.base-title-wrap .title-content{
    width: 75%;
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    -moz-transform: translateX(-50%);
    -webkit-transform: translateX(-50%);
    height: 1.4rem;
    line-height: 1.4rem;
    font-size: 16px;
    color: #fff;
    text-align: center;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}
[data-dpr="2"] .base-title-wrap .title-content{
    font-size: 32px;
}
[data-dpr="3"] .base-title-wrap .title-content{
    font-size: 48px;
}
.columns-box{
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0; 
     overflow-y: auto;
    -webkit-overflow-scrolling: touch;
}
@media (prefers-color-scheme: dark) {
    .columns-box {
        -webkit-filter:brightness(0.5);
        -o-filter:brightness(0.5);
        -moz-filter:brightness(0.5);
        filter:brightness(0.5);
        background: #fff;
    }
}
.dark{
    -webkit-filter:brightness(0.5);
    -o-filter:brightness(0.5);
    -moz-filter:brightness(0.5);
    filter:brightness(0.5);
    background: #fff;
}