.contentbai {
    display: flex;
    background-image: url(../imges/bg3.jpg);
    background-position: 0 0;
    background-attachment: fixed;
    background-repeat: no-repeat;
    background-size: cover;
    height: 900px;
    width: 100%;
    overflow: hidden;
}

.bai {
    display: block;
    width: 1800px;
    height: 650px;
    margin: 100px auto;
    /* left: 70%; */
    overflow: hidden;
    border-radius: 15px;
}



.bai li {
    width: 250px;
    float: left;
    border: left;
    border-left: 1px solid #fff;
    position: relative;
    transition: all 1s;
}

.flag {
    position: absolute;
    left: 0;
    bottom: 0;
    width: 1440%;
    height: 80px;
    line-height: 80px;
    text-align: center;
    color: #fff;
    font-size: 30px;
    font-weight: bold;
    text-align: left;
    background-color: rgb(158, 153, 147, 0.5);
}

.bai:hover li {
    width: 40px;
}

.bai li:hover {
    width: 840px;
}

/* 数字资源 */
.sz:nth-child(1),
.sz:nth-child(3),
.sz:nth-child(6),
.sz:nth-child(8) {
    color: rgb(255, 255, 255);
    background-color: rgba(38, 50, 101, 0.6);
}

.sz:nth-child(2),
.sz:nth-child(4),
.sz:nth-child(5),
.sz:nth-child(7) {
    color: rgba(38, 50, 101, );
    /* background-color: rgb(255, 255, 255); */
}

.rong {
    width: 1650px;
    margin: 5px auto;
}

.math {
    margin: 5px 20px;
    /* display: flex; */
}

.iconfont {

    display: inline-block;
}

.logo a {
    font-size: 60px;
}

i {
    width: 100px;
    height: 100px;
    font-size: 100px;
}

.lei2,
.lei4,
.lei5,
.lei7 {
    display: flex;
    float: left;
    background-color: rgba(255, 255, 255, 0.801);
    margin: 40px auto;
    width: 310px;
    padding: 40px;
    height: 300px;
    text-align: center;
    border: 2px solid #fff;
    border-radius: 15%;

}

/* .math:nth-child(1),
.math:nth-child(3),
.math:nth-child(5),
.math:nth-child(7) {
    background-color: rgba(167, 20, 20, 0.6);
} */
.lei1,
.lei3,
.lei6,
.lei8 {
    background-color: rgba(38, 50, 101, 0.6);
    display: flex;
    float: left;
    /* background-color: rgba(255, 255, 255, 0.801); */
    margin: 40px auto;
    width: 310px;
    padding: 40px;
    height: 300px;
    text-align: center;
    border: 2px solid #fff;
    border-radius: 15%;
}

/* .math li:nth-child(2),
.lei:nth-child(4),
.lei:nth-child(6),
.lei:nth-child(8) {
    color: rgba(38, 50, 101, 0.6);
    background-color: rgb(255, 255, 255);
} */


.lei dl {
    margin: auto;
}

/* .lei:nth-child(2),
.lei:nth-child(4),
.lei:nth-child(6),
.lei:nth-child(8) {
    border: 2px solid rgb(38, 50, 101);
} */

.dcr {
    display: none;
}

.lei:hover {
    .dcr {
        display: block;
    }

    transition: 2s;
    background-color: bisque;
    width: 300px;
}