.bottom-menu {
            position: fixed;
            z-index: 10;
            left: 0;
            right: 0;
            bottom: 0;
            width: 100%;
            background-color:rgba(255,255,255,0.9);
            margin:0; /*很重要*/
        }

        .bottom-menu li {
            float: left;
            list-style: none;

        }

        .bottom-menu a {
            display: block;
            padding: 10px 25px 5px 25px;
            width: 105px;
            text-align: center;
            -webkit-transition: .5s all ease-out;
            -moz-transition: .5s all ease-out;
            transition: .5s all ease-out;
            border-bottom: 3px solid cyan;
            color: #aaa;
            text-decoration: none;
        }

        .bottom-menu a:hover {
            color: #000;
        }

        .bottom-menu li.active a {
            border-bottom: 3px solid #333;
            color: red;
        }