.stamps {
    display: flex;
    justify-content: center;
    margin-bottom: 20px;
}

.stamp {
    width: 60px;
    height: 60px;
    border: 3px solid #ccc;
    border-radius: 50%;
    margin: 0 10px;
    transition: all 0.3s;
    text-align: center;
    line-height: 54px;
    font-size: 2em;
    color: #ccc;
}

.filled {
    color: #8B4513;
    border-color: #8B4513;
}

#free-message {
    font-size: 1.5em;
    color: white;
    background-color: #4CAF50;
    padding: 20px;
    border-radius: 10px;
    margin-bottom: 20px;
}

.hidden {
    display: none;
}

@media (max-width: 480px) {
    .stamp {
        width: 50px;
        height: 50px;
    }
}