.flex{
    display: flex;
}
.flex_sb{
    display: flex;
    justify-content: space-between;
}
.flex_ab{
    display: flex;
    justify-content: space-around;
}
.w1000{
    width: 1000px;
    margin: 0 auto ;
}
.index_ab>div{
    width: 48%;
}
.a2 ,.index_ab p,.a4{
    max-width: 100%;
}
.a4{
    display: flex;
    justify-content: center;
}
.index_ab{
   padding: 30px 20px 0 ;
   
}
.index_ab_tow{
    background: #ffffff;
    padding: 0 ;
}