.clearfix:after {
    content: ".";
    display: block;
    height: 0;
    clear: both;
    visibility: hidden;
}

* {
    margin: 0;
    padding: 0;
}

html {
    height: 100%;
}

.link {
    margin-left: 5px;
}

body {
    height: 100%;
    text-align: center;
}

.header {
    background-color: black;
    height: 100px;
    text-align: center;
    color: #ffffff;
}

.header .center {
    display: inline-block;
    width: 960px;
    height: 100px;
}

.header .link {
    float: right;
    list-style-type: none;
    display: flex;
    padding: 0;
    margin: 0;
}

.header a {
    font-size: 14px;
    color: white;
    text-decoration: none;
}

.banner {
    height: 300px;
    background-color: #00ff006c;
}

.banner .back {
    width: 960px;
    display: inline-block;
}

.banner .tab {
    position: relative;
    display: inline-block;
    float: right;
    height: 47px;
    margin-top: 180px;
    vertical-align: bottom;
    /*垂直对齐图像*/
    padding: 0;
    font-size: 0;
}

.banner li {
    text-align: center;
    padding: 0;
    position: relative;
    display: inline-block;
    width: 30px;
    height: 40px;
    margin-left: 8px;
    font-size: 15px;
    vertical-align: bottom;
    border: 1px solid gold;
    background: #c0c0a0;
}

.banner li a.active {
    font-weight: bold;
    height: 55px;
    background: #ffffff;
}

.banner li a:focus,
.banner li a:hover {
    /*可视化反馈*/
    font-weight: bold;
    height: 55px;
}

.navi {
    font-size: 0;
    /*解决inline元素间的空白间隙*/
    position: relative;
    width: 100%;
    margin-top: 20px;
    text-align: center;
}

.navi ul {
    list-style-type: none;
    padding: 0;
    margin: 0;
    display: inline-block;
    width: 960px;
    position: relative;
}

.navi li {
    float: left;
    list-style-type: none;
    margin: 0;
    padding: 0;
}

.navi li a {
    font-size: 15px;
    position: relative;
    display: block;
    text-decoration: none;
    width: 150px;
    line-height: 3;
    padding: 0;
    margin: 0;
    background-color: #c0c0a0;
    border-top: 1px solid grey;
    border-left: 1px solid grey;
    border-right: 1px solid grey;
    color: black;
    text-align: center;
    border-radius: 30px 30px 0 0;
}

.navi li a:focus,
.navi li a:hover {
    /*可视化反馈*/
    font-weight: bold;
}

.navi li a.active {
    background-color: white;
    font-weight: bold;
    border-bottom: white;
}

.line {
    height: 1px;
    width: 100%;
    position: absolute;
    z-index: 0;
    /*创建一个新的层叠上下文 */
    clear: both;
    background: grey;
    margin-top: -1px;
}

.content {
    position: relative;
    width: 960px;
    height: 160px;
    margin-top: 10px;
    display: inline-block;
}

.content ul {
    list-style-type: none;
    width: 100%;
    height: 100%;
    display: flex;
}

.content li {
    list-style-type: none;
    border: 1px solid grey;
    margin: 0 4px 0 4px;
    flex: 1;
}

.footer {
    background-color: grey;
    color: white;
    text-align: center;
    padding: 20px;
    margin-top: 10px;
    font-size: 14px;
    height: 80px;
}