#hc-retro {
    max-width: 650px;
    margin: 20px auto;
    padding: 30px;
    background: #ffffff;
    border-radius: 20px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
    font-family: 'Inter', sans-serif;
    border-left: 5px solid #34495e;
}

#hc-retro .hc-header h3 {
    color: #34495e;
}

#hc-retro .hc-btn {
    background: #34495e;
}

#hc-retro .hc-btn:hover {
    background: #2c3e50;
}

#hc-retro .hc-result {
    background: #f4f7f6;
    border: 1px solid #34495e;
}

#hc-retro .hc-result-value {
    color: #e74c3c;
    font-weight: 700;
}

@media (max-width: 480px) {
    #hc-retro .hc-form-row {
        flex-direction: column;
    }
}