@media screen and (min-width:320px) and (max-device-width:640px) {
    *{
        box-sizing: border-box;
    }
    #retail{
        width: 100%;
    }
    .retail{
        width: 100%;
        margin: 0 auto;
    }
    .retaSection {
        width: 100%;
    }
    .retaSection h3 {
        height: auto;
        line-height: 1.5;
        font-size: 32px;
        padding-top: 12%;
        margin-bottom: 5%;
    }
    #banner {
        width: 100%;
        height: 100%;
        background-size: cover;
    }
    #bannerPic {
        width:100%;
    }
    #bannerPic img {
        max-width: 80%;
        left: 5%;
        top: 25%;
    }

    .bannerBtn {
        width: 100%;
        left: 50%;
        margin-left: -48%;
        top:50%;
    }

    .bannerBtn span {
        padding-left: 8%;
        font-size: 20px;
        height: auto;
        line-height: 1.8;
    }

    .bannerBtn2 {
        margin-left: 0;
    }
    .retail1 h2{
        width: 100%;
        height: auto;
        line-height: 1.6;
        /* line-height: normal; */
        font-size: 26px;
        background-size: 100%;
        margin: 10% auto 0;
    }
    .retail1 .retaSection {
        width: 100%;
        margin: 0 auto;
        overflow: hidden;
        position: relative;
    }
    .caseContainer {
        width: 100%;
        position: absolute;
        top: 25%;
        left: 0;
    }
    .caseBlock {
        width: 100%;
        float:none;
    }
    .caseBlock .left{
        width: 100%;
    }
    .retail2 {
        width: 100%;
        height: 100%;
        background-size: cover;
    }
    .retail2Ul {
        width: 100%;
    }
    .retail2Ul li {
       width: 22%;
        margin: 0 1%;
    }
    .retail2Ul li p {
        display: initial;
        width: 22%;
        margin-left: 1%;
        font-size: 14px;
    }
    .retail3 {
        width: 100%;
        padding-bottom:20%;
    }
    .retail4 {
        width: auto;
        height: 100%;
        background-size: cover;
    }
    .retail4 .btnGroup {
        width: 100%;
        height: auto;
        margin: 0 auto 2%;
    }
    .retail4 .btnGroup span {
        width: 30%;
        font-size: 20px;
    }
    .retail4 .caseContainer {
        width: 300%;
        top:30%;
    }
    .retail4 .caseContainer .caseBlock>img{
        max-width: 100%;
    }
    .retail4 h4 {
        margin-bottom: 2%;
        font-size: 16px;
        text-align: center;
    }
    #Extend {
        width: 100%;
    }
    #Extend1 {
        width: 40%;
    }
    #Extend1 img {
        margin-left: 1%;
    }
    .des2 {
        width:100%;
        margin: 0 auto;
    }
}