body:before {
    background: url(https://img2020.cnblogs.com/blog/2171939/202010/2171939-20201020182146856-1540185035.png) center/cover no-repeat;
    content: '';
    background-repeat: no-repeat;
    background-position: center;
    opacity: 0.1;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    -webkit-filter: grayscale(40%);
    -moz-filter: grayscale(40%);
    -ms-filter: grayscale(40%);
    -o-filter: grayscale(40%);
    filter: grayscale(40%);
    filter: gray;
}
//滚动条
.scroller-offset1 {text-indent: 0 /* !important */;}
.scroller-offset2 {text-indent: 1.5em;}
.scroller-offset3 {text-indent: 3em;}
.scroller-offset4 {text-indent: 4.5em;}
.scroller-offset5 {text-indent: 6em;}
.scroller-offset6 {text-indent: 7.5em;}
.nav .active {background-color:#f5f5f5;}