.flex_box {
    display: flex;
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: center;
}

    .flex_box > div {
        width: 400px;
        margin: 10px;
        text-align: center;
        border-radius: 10px;
        border: 1px solid #AD27c1;
        background-color: #e6eeff;
    }