.tit-nav-li:nth-child(5) {
        background-color: #638df9;
    }
    
    .tit-nav-li:nth-child(5) a {
        color: white;
    }
    
    .ban-tit {
        width: 100%;
        height: 300px;
        background: url("../upload/intro.png") no-repeat;
        background-size: 100%;
        overflow: hidden;
        margin-bottom: 20px;
    }
    
    .bg-tit {
        width: 300px;
        height: 100px;
        text-align: center;
        margin: 0 auto;
        margin-top: 70px;
    }
    
    .bg-tit h2 {
        width: 300px;
        height: 50px;
        line-height: 50px;
        font-size: 36px;
        font-weight: 300;
        color: white;
        letter-spacing: 5px;
    }
    
    .bg-tit h3 {
        width: 300px;
        height: 35px;
        line-height: 35px;
        font-size: 18px;
        font-weight: 300;
        color: white;
        letter-spacing: 2px;
    }
    
    .intro-tit {
        width: 650px;
        height: 50px;
        margin: 0 auto;
        margin-bottom: 50px;
    }
    
    .sidel,
    .sider {
        float: left;
        width: 200px;
        height: 48px;
    }
    
    .sidel {
        border-bottom: 2px solid #aed4f5;
    }
    
    .sider {
        border-top: 2px solid #aed4f5;
    }
    
    .sidec {
        float: left;
        width: 200px;
        height: 50px;
        text-align: center;
        line-height: 50px;
        font-size: 26px;
        font-weight: 500;
        color: #40a2f5;
        letter-spacing: 5px;
    }
    
    .intro-cont {
        width: 1200px;
        margin: 0 auto;
        font-size: 14px;
        text-indent: 2em;
        line-height: 30px;
        letter-spacing: 2px;
        margin-bottom: 20px;
    }
    
    .certf-kid {
        margin: 0 auto;
        width: 85%;
        height: auto;
        display: flex;
        justify-content: space-around;
        flex-wrap: wrap;
    }
    
    .certf-pic-kid {
        width: 300px;
        height: auto;
        margin-bottom: 30px;
    }
    
    .certf-pic {
        width: 250px;
        height: 400px;
        overflow: hidden;
        margin: 0 auto;
        margin-bottom: 10px;
    }
    
    .certf-pic img {
        width: 100%;
        height: 100%;
    }
    
    .certf-txt {
        width: 250px;
        height: auto;
        margin: 0 auto;
        text-align: left;
        line-height: 30px;
        white-space: normal;
        font-size: 16px;
        color: black;
    }