.tr-buzhou {
    display: flex;
    flex-wrap: wrap-reverse;
}
.tr-buzhoua {
    border: 1px solid #999999;
    padding: 10px;
    margin: 5px;
    width: 31%;
    box-sizing: border-box;
}
@media screen and (max-width: 750px){
.tr-buzhoua {
    width: 100%;
}
}