* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background: linear-gradient(135deg, #ff6b6b 0%, #feca57 100%);
            min-height: 100vh;
            padding: 40px 20px;
        }
        .container {
            max-width: 700px;
            margin: 0 auto;
            background: white;
            border-radius: 20px;
            padding: 40px;
            box-shadow: 0 20px 60px rgba(0,0,0,0.3);
        }
        h1 {
            text-align: center;
            color: #333;
            margin-bottom: 30px;
            font-size: 2em;
        }
        .calc-type {
            display: grid;
            grid-template-columns: repeat(2, 1fr);
            gap: 10px;
            margin-bottom: 30px;
        }
        .type-btn {
            padding: 15px;
            border: 2px solid #e0e0e0;
            background: white;
            border-radius: 8px;
            cursor: pointer;
            font-weight: 600;
            transition: all 0.3s;
        }
        .type-btn.active {
            background: linear-gradient(135deg, #ff6b6b 0%, #feca57 100%);
            color: white;
            border-color: transparent;
        }
        .calculator-section {
            display: none;
            padding: 20px;
            background: #f9f9f9;
            border-radius: 12px;
        }
        .calculator-section.active {
            display: block;
        }
        .input-row {
            display: flex;
            align-items: center;
            gap: 10px;
            margin-bottom: 20px;
        }
        input {
            flex: 1;
            padding: 12px;
            border: 2px solid #e0e0e0;
            border-radius: 8px;
            font-size: 16px;
            transition: border-color 0.3s;
        }
        input:focus {
            outline: none;
            border-color: #ff6b6b;
        }
        .operator {
            font-size: 20px;
            font-weight: bold;
            color: #666;
        }
        .result {
            background: linear-gradient(135deg, #ff6b6b 0%, #feca57 100%);
            color: white;
            padding: 25px;
            border-radius: 12px;
            text-align: center;
            margin-top: 20px;
        }
        .result-value {
            font-size: 2.5em;
            font-weight: bold;
        }
        button {
            width: 100%;
            padding: 14px;
            background: linear-gradient(135deg, #95a5a6 0%, #7f8c8d 100%);
            color: white;
            border: none;
            border-radius: 8px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: transform 0.2s;
            margin-top: 20px;
        }
        button:hover {
            transform: translateY(-2px);
        }
        label {
            display: block;
            margin-bottom: 8px;
            color: #555;
            font-weight: 600;
            font-size: 14px;
        }