body {
    font-family: Arial, sans-serif;
    text-align: center;
    padding: 20px;
}

.box {
    padding: 30px;
    margin: 20px;
    background: lightgray;
}

/* Mobile */
@media (max-width: 600px) {
    body {
        background: #500b1f;
    }
    .box {
        font-size: 14px;
    }
}

/* Tablet */
@media (min-width: 601px) and (max-width: 900px) {
    body {
        background: #7da143;
    }
    .box {
        font-size: 18px;
    }
}

/* Desktop */
@media (min-width: 901px) {
    body {
        background: #0084ff;
    }
    .box {
        font-size: 22px;
    }
}

.observation {
    margin-top: 40px;
    padding: 15px;
    border: 2px dashed #444;
}