:root {
            --primary: #10b981;
            --primary-light: #34d399;
            --secondary: #f59e0b;
            --accent: #8b5cf6;
            --bg-primary: #f9fafb;
            --surface-elevated: #ffffff;
            --text-primary: #111827;
            --text-secondary: #6b7280;
            --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
            --space-sm: 0.5rem;
            --space-md: 1rem;
            --space-lg: 1.5rem;
            --space-xl: 2rem;
            --space-2xl: 3rem;
            --radius-md: 12px;
            --radius-lg: 16px;
            --radius-xl: 24px;
            --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
            --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
            --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
            --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
        }
        
        * { 
            margin: 0; 
            padding: 0; 
            box-sizing: border-box; 
        }
        
        body {
            font-family: var(--font-primary);
            background: linear-gradient(135deg, #f0f9ff 0%, #ecfdf5 50%, #fefce8 100%);
            color: var(--text-primary);
            line-height: 1.6;
            min-height: 100vh;
        }
        
        .container {
            max-width: 900px;
            margin: 0 auto;
            padding: 0 var(--space-xl);
        }
        
        .main-content {
            padding: var(--space-2xl) 0;
        }
        
        .calculator-card {
            background: rgba(255, 255, 255, 0.9);
            backdrop-filter: blur(20px);
            border-radius: var(--radius-xl);
            box-shadow: var(--shadow-xl);
            border: 1px solid rgba(255, 255, 255, 0.2);
            overflow: hidden;
            position: relative;
        }
        
        .calculator-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            height: 4px;
            background: linear-gradient(90deg, var(--primary), var(--secondary), var(--accent));
        }
        
        .card-header {
            background: linear-gradient(135deg, var(--primary), var(--primary-light));
            color: white;
            padding: var(--space-2xl);
            text-align: center;
        }
        
        .header-icon {
            font-size: 3rem;
            margin-bottom: var(--space-md);
            display: inline-block;
            animation: bounce 2s ease-in-out infinite;
        }
        
        @keyframes bounce {
            0%, 20%, 50%, 80%, 100% { transform: translateY(0); }
            40% { transform: translateY(-10px); }
            60% { transform: translateY(-5px); }
        }
        
        .card-title {
            font-size: clamp(1.75rem, 4vw, 2.5rem);
            font-weight: 800;
            margin-bottom: var(--space-md);
        }
        
        .card-subtitle {
            font-size: 1.125rem;
            opacity: 0.9;
            font-weight: 500;
        }
        
        .card-content {
            padding: var(--space-2xl);
        }
        
        .tab-navigation {
            display: flex;
            background: #f3f4f6;
            border-radius: var(--radius-lg);
            padding: 0.25rem;
            margin-bottom: var(--space-xl);
            overflow-x: auto;
        }
        
        .tab-button {
            flex: 1;
            background: transparent;
            border: none;
            padding: var(--space-md) var(--space-lg);
            border-radius: var(--radius-md);
            font-weight: 600;
            font-size: 0.875rem;
            cursor: pointer;
            transition: var(--transition-base);
            color: var(--text-secondary);
            white-space: nowrap;
        }
        
        .tab-button.active {
            background: white;
            color: var(--primary);
            box-shadow: var(--shadow-md);
        }
        
        .tab-button:hover:not(.active) {
            background: rgba(255, 255, 255, 0.5);
        }
        
        .tab-button:disabled {
            opacity: 0.5;
            cursor: not-allowed;
        }
        
        .tab-content {
            display: none;
        }
        
        .tab-content.active {
            display: block;
            animation: fadeIn 0.4s ease-out;
        }
        
        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(20px); }
            to { opacity: 1; transform: translateY(0); }
        }
        
        .form-group {
            margin-bottom: var(--space-xl);
        }
        
        .form-label {
            display: block;
            font-size: 1.125rem;
            font-weight: 600;
            color: var(--text-primary);
            margin-bottom: var(--space-md);
        }
        
        .form-description {
            font-size: 0.875rem;
            color: var(--text-secondary);
            margin-bottom: var(--space-lg);
        }
        
        .range-input {
            -webkit-appearance: none;
            width: 100%;
            height: 8px;
            border-radius: 50px;
            background: linear-gradient(90deg, var(--primary) 0%, var(--secondary) 100%);
            outline: none;
            cursor: pointer;
            margin-bottom: var(--space-md);
        }
        
        .range-input::-webkit-slider-thumb {
            -webkit-appearance: none;
            width: 24px;
            height: 24px;
            border-radius: 50%;
            background: white;
            border: 3px solid var(--primary);
            cursor: pointer;
            box-shadow: var(--shadow-md);
            transition: var(--transition-base);
        }
        
        .range-input::-webkit-slider-thumb:hover {
            transform: scale(1.1);
        }
        
        .range-labels {
            display: flex;
            justify-content: space-between;
            align-items: center;
            font-size: 0.875rem;
            color: var(--text-secondary);
        }
        
        .range-value {
            background: var(--primary);
            color: white;
            padding: 0.5rem 1rem;
            border-radius: 50px;
            font-weight: 600;
            font-size: 0.875rem;
        }
        
        .btn-primary {
            width: 100%;
            background: linear-gradient(135deg, var(--primary), var(--primary-light));
            color: white;
            border: none;
            padding: var(--space-lg) var(--space-xl);
            border-radius: var(--radius-lg);
            font-size: 1.125rem;
            font-weight: 700;
            cursor: pointer;
            transition: var(--transition-base);
            box-shadow: 0 8px 32px rgba(16, 185, 129, 0.15);
            margin-bottom: var(--space-xl);
        }
        
        .btn-primary:hover {
            transform: translateY(-2px);
            box-shadow: 0 12px 40px rgba(16, 185, 129, 0.2);
        }
        
        .btn-primary:disabled {
            opacity: 0.7;
            cursor: not-allowed;
            transform: none;
        }
        
        .simple-message {
            text-align: center;
            padding: var(--space-2xl);
            background: white;
            border-radius: var(--radius-lg);
            margin: var(--space-xl) 0;
            box-shadow: var(--shadow-md);
        }
        
        .simple-message h2 {
            color: var(--primary);
            margin-bottom: var(--space-md);
        }
        
        @media (max-width: 768px) {
            .container {
                padding: 0 var(--space-md);
            }
            
            .card-content {
                padding: var(--space-lg);
            }
        }