.error-message {
    background: #f8d7da;
    border: 1px solid #f5c6cb;
    color: #721c24;
    padding: 15px;
    border-radius: 5px;
    margin: 20px 0;
    display: none;
}

.error-message.show {
    display: block;
}

.error-message strong {
    display: block;
    margin-bottom: 5px;
}