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

        body {
            font-family: 'Segoe UI', system-ui, sans-serif;
            min-height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
            background: #f8fafc;
            padding: 20px;
        }

        .calculator {
            background: white;
            border-radius: 16px;
            box-shadow: 0 12px 40px rgba(0,0,0,0.08);
            display: flex;
            gap: 2rem;
            padding: 2.5rem;
            max-width: 900px;
            width: 100%;
            border: 1px solid #e2e8f0;
        }

        .input-section {
            flex: 1;
            display: flex;
            flex-direction: column;
            gap: 1.5rem;
        }

        .result-section {
            flex: 0 0 300px;
            padding-left: 2rem;
            border-left: 2px solid #e2e8f0;
            display: flex;
            flex-direction: column;
            justify-content: center;
        }

        h1 {
            color: #1e293b;
            font-size: 1.8rem;
            margin-bottom: 1rem;
        }

        .input-group {
            display: flex;
            flex-direction: column;
            gap: 0.5rem;
        }

        label {
            color: #475569;
            font-size: 0.95rem;
            font-weight: 500;
        }

        input {
            padding: 0.8rem 1rem;
            border: 2px solid #cbd5e1;
            border-radius: 8px;
            font-size: 1rem;
            transition: all 0.2s ease;
        }

        input:focus {
            border-color: #3b82f6;
            outline: none;
            box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
        }

        input[readonly] {
            background: #f1f5f9;
            cursor: not-allowed;
        }

        button {
            background: #3b82f6;
            color: white;
            padding: 1rem;
            border: none;
            border-radius: 8px;
            font-size: 1rem;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.2s ease;
            margin-top: 1rem;
        }

        button:hover {
            background: #2563eb;
            transform: translateY(-1px);
        }

        .result-item {
            background: #f1f5f9;
            padding: 1.2rem;
            border-radius: 8px;
            margin-bottom: 1.2rem;
        }

        .result-item h3 {
            color: #64748b;
            font-size: 0.9rem;
            margin-bottom: 0.5rem;
        }

        .result-value {
            font-size: 1.5rem;
            font-weight: 700;
            color: #1e293b;
        }

        .error-message {
            color: #dc2626;
            font-size: 0.8rem;
            margin-top: 4px;
            display: none;
        }

        @media (max-width: 768px) {
            .calculator {
                flex-direction: column;
                padding: 1.5rem;
                max-width: 500px;
            }

            .result-section {
                border-left: none;
                border-top: 2px solid #e2e8f0;
                padding: 1.5rem 0 0;
                margin-top: 1.5rem;
            }
        }