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

        :root {
            --primary-color: #4f46e5;
            --primary-dark: #4338ca;
            --secondary-color: #06b6d4;
            --success-color: #10b981;
            --danger-color: #ef4444;
            --warning-color: #f59e0b;
            --light-bg: #f8fafc;
            --dark-text: #1e293b;
            --gray-text: #64748b;
        }

        body {
            font-family: 'Inter', 'Poppins', sans-serif;
            line-height: 1.6;
            color: var(--dark-text);
            background: #ffffff;
        }

        /* Hero Section */
        .hero-section {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            padding: 20px 0 60px;
            position: relative;
            overflow: hidden;
        }

        .hero-section::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: url('data:image/svg+xml,<svg width="100" height="100" xmlns="http://www.w3.org/2000/svg"><rect fill="rgba(255,255,255,0.05)" width="50" height="50"/></svg>');
            opacity: 0.3;
        }

        .hero-content {
            position: relative;
            z-index: 2;
        }

        .hero-section .badge {
            font-size: 0.875rem;
            padding: 0.5rem 1rem;
            border-radius: 50px;
            background: rgba(255, 255, 255, 0.2);
            backdrop-filter: blur(10px);
        }

        .hero-section h1 {
            font-size: 3rem;
            font-weight: 700;
            margin-top: 1rem;
            text-shadow: 2px 2px 4px rgba(0,0,0,0.1);
        }

        .hero-image img {
            border-radius: 20px;
            box-shadow: 0 20px 60px rgba(0,0,0,0.3);
            animation: float 6s ease-in-out infinite;
        }

        @keyframes float {
            0%, 100% { transform: translateY(0px); }
            50% { transform: translateY(-20px); }
        }

        /* Interactive Mind Map Styles */
        .mindmap-container {
            background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
            border-radius: 20px;
            padding: 40px 20px;
            margin: 40px 0;
            box-shadow: 0 10px 40px rgba(0,0,0,0.1);
        }

        .header {
            text-align: center;
            margin-bottom: 30px;
        }

        .header .icon {
            font-size: 3rem;
            color: var(--primary-color);
            margin-bottom: 15px;
        }

        .header h3 {
            color: var(--dark-text);
            font-weight: 600;
        }

        .control-panel {
            margin: 30px 0;
        }

        .btn-control {
            padding: 12px 24px;
            border-radius: 50px;
            font-weight: 500;
            transition: all 0.3s ease;
            border: none;
            box-shadow: 0 4px 15px rgba(0,0,0,0.1);
        }

        .btn-expand {
            background: var(--success-color);
            color: white;
        }

        .btn-expand:hover {
            background: #059669;
            transform: translateY(-2px);
            box-shadow: 0 6px 20px rgba(16, 185, 129, 0.4);
        }

        .btn-collapse {
            background: var(--warning-color);
            color: white;
        }

        .btn-collapse:hover {
            background: #d97706;
            transform: translateY(-2px);
            box-shadow: 0 6px 20px rgba(245, 158, 11, 0.4);
        }

        .btn-reset {
            background: var(--primary-color);
            color: white;
        }

        .btn-reset:hover {
            background: var(--primary-dark);
            transform: translateY(-2px);
            box-shadow: 0 6px 20px rgba(79, 70, 229, 0.4);
        }

        .mindmap {
            display: flex;
            flex-direction: column;
            align-items: center;
            gap: 20px;
        }

        .node {
            background: white;
            padding: 15px 25px;
            border-radius: 12px;
            box-shadow: 0 4px 15px rgba(0,0,0,0.1);
            transition: all 0.3s ease;
            position: relative;
            font-weight: 500;
            display: flex;
            align-items: center;
            gap: 10px;
            cursor: default;
        }

        .node i {
            font-size: 1.2rem;
        }

        .node.root {
            background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
            color: white;
            font-size: 1.3rem;
            padding: 20px 35px;
            box-shadow: 0 8px 25px rgba(79, 70, 229, 0.3);
        }

        .node.clickable {
            cursor: pointer;
            background: linear-gradient(135deg, #667eea, #764ba2);
            color: white;
        }

        .node.clickable:hover {
            transform: translateY(-3px);
            box-shadow: 0 8px 25px rgba(102, 126, 234, 0.4);
        }

        .node.clickable.expanded {
            background: linear-gradient(135deg, var(--success-color), #059669);
        }

        .children {
            display: flex;
            flex-direction: column;
            gap: 15px;
            padding-left: 40px;
            border-left: 3px solid var(--primary-color);
            margin-left: 20px;
        }

        .children.root-level {
            padding-left: 0;
            border-left: none;
            margin-left: 0;
            width: 100%;
        }

        /* Key Concepts Section */
        .key-concepts-section {
            background: var(--light-bg);
        }

        .section-header {
            margin-bottom: 3rem;
        }

        .section-header h2 {
            font-size: 2.5rem;
            color: var(--dark-text);
            font-weight: 700;
        }

        .concept-card {
            background: white;
            padding: 2rem;
            border-radius: 15px;
            box-shadow: 0 5px 20px rgba(0,0,0,0.08);
            transition: all 0.3s ease;
            height: 100%;
            border-top: 4px solid var(--primary-color);
        }

        .concept-card:hover {
            transform: translateY(-10px);
            box-shadow: 0 15px 40px rgba(0,0,0,0.15);
        }

        .concept-icon {
            font-size: 3rem;
            color: var(--primary-color);
            margin-bottom: 1rem;
        }

        .concept-card h3 {
            font-size: 1.5rem;
            font-weight: 600;
            margin-bottom: 1rem;
            color: var(--dark-text);
        }

        .example-box {
            background: var(--light-bg);
            padding: 1rem;
            border-radius: 10px;
            margin-top: 1rem;
            border-left: 4px solid var(--secondary-color);
        }

        /* Rules Section */
        .rules-card {
            background: white;
            padding: 2.5rem;
            border-radius: 20px;
            box-shadow: 0 10px 40px rgba(0,0,0,0.1);
        }

        .rule-step {
            display: flex;
            gap: 2rem;
            margin-bottom: 2rem;
            padding-bottom: 2rem;
            border-bottom: 2px solid var(--light-bg);
        }

        .rule-step:last-child {
            border-bottom: none;
            margin-bottom: 0;
        }

        .step-number {
            width: 50px;
            height: 50px;
            background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
            color: white;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.5rem;
            font-weight: 700;
            flex-shrink: 0;
        }

        .step-content h4 {
            font-size: 1.25rem;
            font-weight: 600;
            margin-bottom: 0.5rem;
            color: var(--dark-text);
        }

        /* Examples Section */
        .example-group {
            background: white;
            padding: 2rem;
            border-radius: 15px;
            box-shadow: 0 5px 20px rgba(0,0,0,0.08);
            height: 100%;
        }

        .example-group h4 {
            font-size: 1.3rem;
            font-weight: 600;
            margin-bottom: 1.5rem;
            color: var(--dark-text);
        }

        .example-list {
            list-style: none;
            padding: 0;
        }

        .example-list li {
            padding: 0.75rem 0;
            border-bottom: 1px solid var(--light-bg);
            font-size: 1.05rem;
        }

        .example-list li:last-child {
            border-bottom: none;
        }

        .example-list li strong {
            color: var(--primary-color);
            font-weight: 600;
        }

        /* Quiz Section */
        .quiz-container {
            background: white;
            padding: 2.5rem;
            border-radius: 20px;
            box-shadow: 0 10px 40px rgba(0,0,0,0.1);
        }

        .quiz-question {
            margin-bottom: 2.5rem;
            padding: 2rem;
            background: var(--light-bg);
            border-radius: 15px;
            border-left: 5px solid var(--primary-color);
        }

        .question-text {
            font-size: 1.2rem;
            font-weight: 500;
            margin-bottom: 1.5rem;
            color: var(--dark-text);
        }

        .form-check {
            margin-bottom: 1rem;
            padding: 1rem;
            background: white;
            border-radius: 10px;
            transition: all 0.3s ease;
        }

        .form-check:hover {
            background: #f1f5f9;
            transform: translateX(5px);
        }

        .form-check-input:checked ~ .form-check-label {
            color: var(--primary-color);
            font-weight: 600;
        }

        .results-container .alert {
            border-radius: 15px;
            padding: 2rem;
        }

        .answer-review {
            padding: 1.5rem;
            margin-bottom: 1rem;
            border-radius: 12px;
            border-left: 5px solid;
        }

        .answer-review.correct {
            background: #d1fae5;
            border-color: var(--success-color);
        }

        .answer-review.incorrect {
            background: #fee2e2;
            border-color: var(--danger-color);
        }

        /* FAQ Section */
        .accordion-item {
            border: none;
            margin-bottom: 1rem;
            border-radius: 12px;
            overflow: hidden;
            box-shadow: 0 4px 15px rgba(0,0,0,0.08);
        }

        .accordion-button {
            font-size: 1.1rem;
            font-weight: 600;
            padding: 1.5rem;
            background: white;
            color: var(--dark-text);
        }

        .accordion-button:not(.collapsed) {
            background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
            color: white;
        }

        .accordion-body {
            padding: 1.5rem;
            font-size: 1.05rem;
            line-height: 1.8;
        }

        /* Responsive Design */
        @media (max-width: 768px) {
            .hero-section h1 {
                font-size: 2rem;
            }

            .section-header h2 {
                font-size: 1.8rem;
            }

            .node {
                font-size: 0.9rem;
                padding: 12px 18px;
            }

            .children {
                padding-left: 20px;
            }
        }

        /* Loading Animation */
        .loading {
            animation: pulse 0.6s ease-in-out;
        }

        @keyframes pulse {
            0%, 100% { transform: scale(1); }
            50% { transform: scale(1.05); }
        }