body {
    background: #000;
}

.img_center {
    align: center;
}

.tel {
    color: white;
    font-size: 4em;
}

.detail_courriel {
    color: white;
    font-size: 2em;
}

._courriel {
    color: white;
    font-size: 2em;
}

@media screen and (max-width: 576px) {
    h1.tel {
        font-size: 2em;
    }

    h1.detail_courriel {
        font-size: 2em;
    }

    h2._courriel {
        font-size: 1em;
    }
}