.my-calc-error {
    background-color: #f8d7da;
    color: #721c24;
    padding: 15px 20px;
    margin: 20px 0;
    border: 1px solid #f5c6cb;
    border-left: 4px solid #dc3545;
    border-radius: 5px;
    font-size: 14px;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Arial, sans-serif;
}

.my-calc-error::before {
    content: "⚠️ ";
    font-size: 1.2em;
    margin-right: 5px;
}