#reader {
    width: 100%;
    min-height: 300px;
    background-color: #f0f0f0;
    border: 1px solid #ddd;
    margin-bottom: 20px;
}

.error-message {
    color: red;
    padding: 20px;
    text-align: center;
}

#stop-scanning {
    display: none;
}