@media only screen and (max-width: 780px){
    .introduce{
        border: 1px solid red;
        clear: both;

    }
    .introduce_div{
        border: 1px solid red;
        display: flex;
        flex-wrap: wrap;
    }
    .introduce_img{
        width: 100%;
    }
    .introduce_text{
        width: 100%;
        border: 1px solid red;
    }
}