* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    min-height: 100vh;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 2rem 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

.container {
    max-width: 600px;
}

.calculator-card {
    margin-top: 2rem;
}

.card {
    border: none;
    border-radius: 15px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
    overflow: hidden;
}

.card-header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 1.5rem;
    border: none;
}

.card-header h1 {
    color: white;
    font-weight: 600;
    font-size: 1.8rem;
}

.card-body {
    padding: 2rem;
}

.form-label {
    font-weight: 600;
    color: #333;
    margin-bottom: 0.5rem;
}

.form-control {
    padding: 0.75rem 1rem;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 1rem;
    transition: all 0.3s ease;
}

.form-control:focus {
    border-color: #667eea;
    box-shadow: 0 0 0 0.2rem rgba(102, 126, 234, 0.25);
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border: none;
    padding: 0.8rem;
    font-weight: 600;
    border-radius: 8px;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 20px rgba(102, 126, 234, 0.4);
    background: linear-gradient(135deg, #764ba2 0%, #667eea 100%);
}

.btn-secondary {
    background: #6c757d;
    border: none;
    padding: 0.8rem;
    font-weight: 600;
    border-radius: 8px;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.btn-secondary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 20px rgba(108, 117, 125, 0.4);
    background: #5a6268;
}

.result-section {
    display: none;
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.result-section h3 {
    color: #333;
    font-weight: 600;
    font-size: 1.5rem;
}

.result-box {
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    padding: 1.5rem;
    border-radius: 10px;
    text-align: center;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.result-label {
    font-size: 0.9rem;
    color: #555;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.result-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: #667eea;
    margin-bottom: 0;
}

@media (max-width: 576px) {
    .card-body {
        padding: 1.5rem;
    }
    
    .card-header h1 {
        font-size: 1.5rem;
    }
    
    .result-value {
        font-size: 1.2rem;
    }
}