body {
    background-image: url("https://images.cnblogs.com/cnblogs_com/blogs/735822/galleries/2117803/o_220303013302_arsneal.jpg");
    background-repeat: repeat-y;
    background-size: 100%;
}
.navbar-custom {
  display: flex;
}
#home {
    margin: 0 auto;
    width: 65%;
    min-width: 950px;
    background-color: #fff;
    padding: 30px;
    margin-top: 82px;
    margin-bottom: 50px;
    box-shadow: 0 2px 6px rgba(100,100,100,.3);
    opacity: 0.95;
    border-radius: 5px;
}

::-webkit-scrollbar {
    /*滚动条整体样式*/
    width : 10px;  /*高宽分别对应横竖滚动条的尺寸*/

  }
::-webkit-scrollbar-thumb {
        /*滚动条里面小方块*/
        border-radius   : 10px;
        background-color: rgba(0,0,0,0.2);
        background-image: -webkit-linear-gradient(
            45deg,
            rgba(255, 255, 255, 0.2) 25%,
            transparent 25%,
            transparent 50%,
            rgba(255, 255, 255, 0.2) 50%,
            rgba(255, 255, 255, 0.2) 75%,
            transparent 75%,
            transparent
        );
  }
::-webkit-scrollbar-track {
    /*滚动条里面轨道*/
    box-shadow   : inset 0 0 5px rgba(0, 0, 0, 0.2);
    background   : #ededed;
    border-radius: 10px;
  }

/*默认样式，主要是position:fixed实现屏幕绝对定位*/
//#gotoTop{display:none;position:fixed;top:75%;left:50%;cursor:pointer;margin-top:-50px;margin-left:520px;padding:9px 4px;width:20px;text-align:center;border:1px solid #e0e0e0;background:#fff;}
#gotoTop{display:none;position:fixed;top:75%;left:50%;cursor:pointer;margin-top:-50px;margin-left:520px;width:150px;height:174px;background:url("https://images.cnblogs.com/cnblogs_com/blogs/735822/galleries/2118066/o_220303045727_back.png") no-repeat;background-position:-600px 0;z-index:999;}
/*用CSS表达式(expression)来实现ie6下position:fixed效果*/
//#gotoTop{_position:absolute;_top:expression(documentElement.scrollTop + documentElement.clientHeight * 3/4 + "px")}
/*鼠标进入的反馈效果*/
//#gotoTop.hover{background:#5CB542;color:#fff;text-decoration:none;}
#gotoTop.hover {animation:back .5s steps(5) infinite}@keyframes back{from{background-position:0 0}to{background-position:-750px 0}}