.middle {
    padding: 50px 0 100px;
}
.product-list {
    width: 900px;
    height: auto;
    margin: 0 auto;
    position: relative;
    overflow: hidden;
}
.product-list li {
    width: 900px;
    height: 404px;
    margin: 15px auto 0;
    position: relative;
    display: flex;
    justify-content: space-between;
}
.product-list li img {
    display: block;
}
.product-intro {
    width: 348px;
    height: 404px;
    position: relative;
}
.product-intro-tit {
    color: #343434;
    font-size: 20px;
    font-weight: 600;
    line-height: 32px;
    margin: 0 auto 12px;
}
.product-intro-txt {
    color: #6e6e6e;
    font-size: 14px;
    line-height: 32px;
    text-align: justify;
    margin: 0 auto;
}