.nav {
    width: 1200px;
    margin: 0 auto;
    height: 40px;
    line-height: 40px;
}

.shouye {
    cursor: pointer;
}

.shouye:hover {
    color: #7BA7AB;
    text-decoration: none;
}

.banner {
    width: 1200px;
    margin: 0 auto;
    display: flex;
    max-height: 320px;
}

.b-left img {
    width: 540px;
    max-height: 320px;
}

.b-right {
    margin-left: 20px;
}

.br-title {
    font-size: 40px;
    line-height:100px;
    color: #666;
    font-weight: 700;
    font-family: "Verdana", sans-serif;
    letter-spacing: 5px;
}

.price {
    font-size: 30px;
    color: #F01414;
    font-weight: 800;
    margin-top: 10px;
}

.br-detail {
    width: 100%;
    padding-right: 3px;
    height: 150px;
    color: #666;
    overflow-y: auto;
}

/*滚动条整体样式*/
.br-detail::-webkit-scrollbar {
    width: 5px;
    height: 1px;
}

/*滚动条滑块*/
.br-detail::-webkit-scrollbar-thumb {
    border-radius: 10px;
    -webkit-box-shadow: inset 0 0 5px rgba(0, 0, 0, 0.2);
    background: #666;
}

/*滚动条轨道*/
.br-detail::-webkit-scrollbar-track {
    -webkit-box-shadow: inset 0 0 1px rgba(0, 0, 0, 0);
    border-radius: 10px;
    background: #ccc;
}
.purchase{
    margin-top: 80px;
}
.price{
    line-height: 30px;
}
.br-btn {
    display: inline-block;
    font-size: 18px;
    width: 120px;
    height: 40px;
    line-height: 40px;
    background-color: #7BA7AB;
    color: #fff;
    font-weight: 600;
    text-align: center;
    letter-spacing: 3px;
    border-radius: 25px;
    cursor: pointer;
    margin-top: 20px;
}

.title-list {
    width: 1200px;
    margin: 0 auto;
    height: 56px;
    line-height: 60px;
}

.title-list li {
    float: left;
    width: 120px;
    font-weight: 600;
    text-align: center;
    margin-left: 10px;
    cursor: pointer;
}

.title-list li:nth-child(3n+1) {
    margin-left: 0px;
}

.title-list li:hover,
.active {
    color: #7BA7AB;
    border-bottom: 4px solid #7BA7AB;
}

.class-content {
    width: 1200px;
    margin: 0 auto;
    min-height: 400px;
}

.class-detail {
    margin-top: 20px;
}

.class-chapter {
    display: none;
    margin-top: 20px;
}

.class-test {
    display: none;
    margin-top: 20px;
}

.cc-title {
    margin-top: 10px;
    height: 40px;
    line-height: 40px;
    margin-left: 15px;
    font-size: 18px;
    font-weight: 700;
    color: #666;
}

.cc-list {
    background-color: #f4f4f4;
    color: #333;
    line-height: 50px;
    padding: 0 35px;
    margin-top: 10px;
    cursor: pointer;
}

.tip {
    font-size: 12px;
    height: 26px;
    line-height: 26px;
    margin: 10px 0px;
    padding: 0px 10px;
    background-color: #7BA7AB;
    color: #fff;
    border-radius: 20px;
    float: right;
    display: none;
}

.cc-list:hover {
    .tip {
        display: inline-block
    }
}

.ct-box {
    width: 280px;
    box-sizing: border-box;
    border-radius: 10px;
    box-shadow: 0 0 7px #bbb;
    text-align: center;
    padding: 10px 15px;
    margin-top: 10px;
    float: left;
    margin-left: 13px;
}

.ct-box:hover {
    color: #7BA7AB;
}
footer{
    margin-top: 30px;
}
@media screen and (max-width: 991px) {
    .nav{
        width: 100%;
    }
    .banner {
        width: 100%;
        display: inline-block;
        max-height: unset;
    }
    .b-left img,
    .title-list,
    .class-content {
        width: 100%;
    }

    .b-right {
        margin-left: 10px;
    }

    .br-title {
        font-size: 20px;
        line-height: 35px;
        letter-spacing: 2px;
    }

    .br-btn {
        font-size: 14px;
        letter-spacing: 0;
        width: 110px;
        height: 33px;
        line-height: 33px;
        display: inline-block;
        margin-left: 30px;
    }

    .purchase {
        /*text-align: right;*/
        margin-top: 0;
    }

    .price {
        font-size: 15px;
        display: inline-block;
    }

    .br-detail {
        font-size: 12px;
    }

    .title-list {
        height: 35px;
        line-height: 35px;
    }

    .title-list li {
        width: 100px;
    }

    .cc-title {
        font-size: 15px;
    }

    .cc-list {
        line-height: 38px;
        padding: 0 25px;
        font-size: 12px;
    }

    .ct-box {
        width: calc(100% - 26px);
        font-size: 12px;
    }
}