/* Lesson-specific CSS extracted from javascript/js.html */

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

        body {
            font-family: 'Segoe UI', Arial, sans-serif;
            background: #f5f5f5;
            padding: 20px;
        }

        .container {
            max-width: 1200px;
            margin: 0 auto;
        }

        h1 {
            color: #333;
            margin-bottom: 30px;
            text-align: center;
        }

        .demo-section {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 20px;
            margin-bottom: 40px;
        }

        /* === 왼쪽: 시각적 데모 === */
        .visual-area {
            background: white;
            border-radius: 8px;
            padding: 20px;
            box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
        }

        .visual-area h2 {
            font-size: 18px;
            margin-bottom: 20px;
            color: #333;
        }

        .section-box {
            position: relative;
            width: 100%;
            height: 200px;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            border: 3px solid #333;
            padding: 20px;
            margin: 30px 0;
            color: white;
            overflow: hidden;
            cursor: crosshair;
        }

        .section-box::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            height: 20px;
            background: rgba(0, 0, 0, 0.2);
            border-bottom: 1px dashed white;
            font-size: 10px;
        }

        .section-box p {
            position: relative;
            z-index: 2;
            font-weight: bold;
            font-size: 14px;
        }

        /* 마우스 위치 표시 */
        .mouse-pointer {
            position: absolute;
            width: 10px;
            height: 10px;
            background: #ffeb3b;
            border: 2px solid white;
            border-radius: 50%;
            transform: translate(-50%, -50%);
            pointer-events: none;
            z-index: 10;
        }

        /* 마우스 좌표 표시 */
        .mouse-coords {
            position: absolute;
            background: rgba(0, 0, 0, 0.7);
            color: #ffeb3b;
            padding: 8px 12px;
            border-radius: 4px;
            font-size: 12px;
            font-weight: bold;
            pointer-events: none;
            z-index: 11;
            white-space: nowrap;
        }

        /* === 오른쪽: 측정값 display === */
        .metrics-area {
            background: white;
            border-radius: 8px;
            padding: 20px;
            box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
        }

        .metrics-area h2 {
            font-size: 18px;
            margin-bottom: 20px;
            color: #333;
        }

        .metric-grid {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 12px;
        }

        .metric-card {
            background: #f9f9f9;
            border-left: 4px solid #667eea;
            padding: 12px;
            border-radius: 4px;
            font-size: 13px;
        }

        .metric-card.element {
            border-left-color: #667eea;
        }

        .metric-card.mouse {
            border-left-color: #ffeb3b;
        }

        .metric-card.window {
            border-left-color: #4caf50;
        }

        .metric-label {
            color: #666;
            font-size: 11px;
            text-transform: uppercase;
            font-weight: bold;
            margin-bottom: 4px;
        }

        .metric-value {
            color: #333;
            font-size: 18px;
            font-weight: bold;
            font-family: 'Courier New', monospace;
        }

        .description-box {
            background: #e3f2fd;
            border-left: 4px solid #2196f3;
            padding: 15px;
            margin: 30px 0;
            border-radius: 4px;
            font-size: 14px;
            line-height: 1.6;
        }

        .description-box strong {
            color: #1976d2;
        }

        @media (max-width: 768px) {
            .demo-section {
                grid-template-columns: 1fr;
            }
        }