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

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            min-height: 100vh;
            padding: 20px;
        }

        .container {
            max-width: 800px;
            margin: 0 auto;
            background: white;
            border-radius: 20px;
            box-shadow: 0 20px 40px rgba(0,0,0,0.1);
            overflow: hidden;
        }

        .header {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            padding: 30px;
            text-align: center;
        }

        .header h1 {
            font-size: 2.5em;
            margin-bottom: 10px;
        }

        .header p {
            font-size: 1.1em;
            opacity: 0.9;
        }

        .content {
            padding: 30px;
        }

        .mode-selector {
            display: flex;
            gap: 10px;
            margin-bottom: 30px;
            flex-wrap: wrap;
        }

        .mode-btn {
            padding: 12px 24px;
            border: none;
            border-radius: 25px;
            background: #f0f0f0;
            color: #333;
            cursor: pointer;
            transition: all 0.3s ease;
            font-size: 14px;
        }

        .mode-btn.active {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
        }

        .mode-btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 5px 15px rgba(0,0,0,0.2);
        }

        .calculator-section {
            display: none;
        }

        .calculator-section.active {
            display: block;
        }

        .input-group {
            margin-bottom: 20px;
        }

        .input-group label {
            display: block;
            margin-bottom: 8px;
            font-weight: 600;
            color: #333;
        }

        .input-group input, .input-group select {
            width: 100%;
            padding: 12px;
            border: 2px solid #e0e0e0;
            border-radius: 10px;
            font-size: 16px;
            transition: border-color 0.3s ease;
        }

        .input-group input:focus, .input-group select:focus {
            outline: none;
            border-color: #667eea;
        }

        .calculate-btn {
            width: 100%;
            padding: 15px;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            border: none;
            border-radius: 10px;
            font-size: 18px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            margin-bottom: 20px;
        }

        .calculate-btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 10px 20px rgba(0,0,0,0.2);
        }

        .result {
            background: #f8f9fa;
            padding: 20px;
            border-radius: 10px;
            border-left: 4px solid #667eea;
            margin-top: 20px;
        }

        .result h3 {
            color: #333;
            margin-bottom: 15px;
        }

        .result-item {
            display: flex;
            justify-content: space-between;
            margin-bottom: 10px;
            padding: 8px 0;
            border-bottom: 1px solid #e0e0e0;
        }

        .result-item:last-child {
            border-bottom: none;
        }

        .result-label {
            font-weight: 600;
            color: #555;
        }

        .result-value {
            font-weight: 700;
            color: #667eea;
        }

        .back-link {
            display: inline-block;
            margin-top: 20px;
            color: #667eea;
            text-decoration: none;
            font-weight: 600;
            transition: color 0.3s ease;
        }

        .back-link:hover {
            color: #764ba2;
        }

        .info-box {
            background: #e3f2fd;
            border: 1px solid #2196f3;
            border-radius: 10px;
            padding: 15px;
            margin-bottom: 20px;
        }

        .info-box h4 {
            color: #1976d2;
            margin-bottom: 10px;
        }

        .info-box p {
            color: #424242;
            line-height: 1.6;
        }

        @media (max-width: 768px) {
            .header h1 {
                font-size: 2em;
            }
            
            .content {
                padding: 20px;
            }
            
            .mode-selector {
                justify-content: center;
            }
        }