@media (max-width: 640px) {
    #talk_body .txt_box {
        max-width: 480px;
        padding: 15px 15px 0px 15px;
        margin: calc(20 / 640 * 100vw) auto calc(30 / 640 * 100vw) auto;
        box-sizing: border-box;
    }
}

@media (min-width: 641px) {
    #talk_body .txt_box {
        max-width: 700px;
        padding: 20px;
        margin: 50px auto 0px auto;
        box-sizing: border-box;
    }
}

@media (max-width: 640px) {
    #talk_body .txt_box .desc p {
        margin: 10px 0 0 0;
        line-height: 1.8em;
        font-size: .85rem;
    }
}

@media (min-width: 641px) {
    #talk_body .txt_box .desc p {
        margin: 30px 0 0 0;
        line-height: 1.8em;
    }
}