html, body {
    margin: 0;
    padding: 0;
    height: 100%;
    width: 100%;
    overflow: hidden;
}

a {
    text-decoration: none;
    color: #000;
}

.wrap {
    display: -webkit-box;
    display: -webkit-flex;
    display: -ms-flexbox;
    display: flex;
    -webkit-box-orient: vertical;
    -webkit-flex-direction: column;
    -ms-flex-direction: column;
    /*布局方向是垂直的*/
    flex-direction: column;
    width: 100%;
    height: 100%;
}

header {
    height: 54px;
    line-height: 54px;
    background-color: #f5f5f5;
    border-bottom: 2px solid #dcdfe6;
}

header .title {
    font-size: 27px;
    margin-left: 15px;
    font-family: "Lucida Calligraphy", cursive, serif, sans-serif;
    font-style: italic;
    font-weight: bold;
}

footer {
    height: 45px;
    line-height: 45px;
    text-align: center;
    background-color: #f5f5f5;
    border-top: 2px solid #dcdfe6;
}

footer a {
    color: #666666;
}

footer a:hover {
    text-decoration: underline;
}

/*设置高度是跟父元素的高度一致，100%；*/
/*实际高度是 100% 减去顶部高度和底部高度，左右两边固定，中间是剩余100%原理一致*/
main {
    -webkit-box-flex: 1;
    -webkit-flex: 1;
    -ms-flex: 1;
    flex: 1;
    width: 100%;
    overflow: auto;
}


main div:first-child {
    margin: 15px;
}

@media screen and (min-width: 90px) and (max-width: 1200px) {
    li {
        width: calc(20% - 5px) !important;
    }
}

@media screen and (min-width: 600px) and (max-width: 900px) {
    li {
        width: calc(33% - 5px) !important;
    }
}

@media screen and (max-width: 600px) {
    li {
        width: 100% !important;
    }
}

ul:after {
    content: "";
    display: block;
    clear: both;
}

ul {
    zoom: 1;
    max-width: 96%;
    margin: 0 auto;
    padding-left: 0;
}

li {
    width: calc(20% - 5px);
    height: auto;
    padding: 50px 0;
    text-align: center;
    margin: 0 5px 10px 0;
    font-size: 28px;
    float: left;
    color: #fff;
    font-weight: bold;
    list-style-type: none;
}