/* 头部开始 */

body {
    position: relative;
    max-width: 640px;
    margin: 0 auto;
}

header {
    text-align: center;
    padding: 0.1rem 0;
    position: relative;
}

header img {
    width: 100%;
}

.nav {
    margin-bottom:2px;
}
.nav ul li {
    float: left;
    width: 33.33%;
    text-align: center;
    background: #3f51b5;
    line-height: 0.4rem;
    border-bottom: 2px solid #fff;
    border-right: 2px solid #fff;
}
.nav ul li:nth-child(3n){
    border-right: 0;
}
.nav ul li:nth-child(4),.nav ul li:nth-child(5),.nav ul li:nth-child(6){
    border-bottom: 0;
}
.nav ul li a {
    color: #fff;
    font-size: 14px;
    display: block;
}

.banner img {
    width: 100%;
}