* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
   
        :root {
            --primary: #4f46e5;
            --primary-dark: #4338ca;
            --primary-light: #6366f1;
            --success: #10b981;
            --danger: #ef4444;
            --warning: #f59e0b;
            --info: #3b82f6;
         
            --bg-primary: #ffffff;
            --bg-secondary: #f8fafc;
            --bg-tertiary: #f1f5f9;
            --text-primary: #0f172a;
            --text-secondary: #475569;
            --text-tertiary: #94a3b8;
            --border: #e2e8f0;
            --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
            --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
            --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
            --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
        }
   
        [data-theme="dark"] {
            --primary: #6366f1;
            --primary-dark: #4f46e5;
            --primary-light: #818cf8;
            --bg-primary: #0f172a;
            --bg-secondary: #1e293b;
            --bg-tertiary: #334155;
            --text-primary: #f1f5f9;
            --text-secondary: #cbd5e1;
            --text-tertiary: #94a3b8;
            --border: #334155;
            --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.3);
            --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.3), 0 2px 4px -2px rgb(0 0 0 / 0.3);
            --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.3), 0 4px 6px -4px rgb(0 0 0 / 0.3);
            --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.4), 0 8px 10px -6px rgb(0 0 0 / 0.4);
        }
   
        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', sans-serif;
            background: var(--bg-primary);
            color: var(--text-primary);
            line-height: 1.6;
            transition: background-color 0.3s, color 0.3s;
            overflow-x: hidden;
        }
      
        /* Premium User Enhancements */
        .premium-welcome {
            text-align: center;
            margin-bottom: 3rem;
        }
      
        .welcome-text {
            font-size: 2rem;
            font-weight: 700;
            color: var(--text-primary);
            margin-bottom: 0.5rem;
        }
      
        .welcome-subtitle {
            color: var(--text-secondary);
            font-size: 1.125rem;
        }
      
        .progress-circle-container {
            display: flex;
            flex-direction: column;
            align-items: center;
            margin: 3rem 0;
        }
      
        .progress-ring {
            position: relative;
            width: 200px;
            height: 200px;
        }
      
        .progress-ring svg {
            transform: rotate(-90deg);
        }
      
        .progress-ring-circle {
            fill: none;
            stroke: var(--border);
            stroke-width: 12;
        }
      
        .progress-ring-progress {
            fill: none;
            stroke: url(#gradient);
            stroke-width: 12;
            stroke-linecap: round;
            transition: stroke-dashoffset 1s ease;
        }
      
        .progress-ring-content {
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            text-align: center;
        }
      
        .progress-percentage {
            font-size: 2.5rem;
            font-weight: 800;
            color: var(--primary);
        }
      
        .progress-label {
            font-size: 0.875rem;
            color: var(--text-secondary);
            text-transform: uppercase;
            letter-spacing: 0.05em;
        }
      
        .progress-stats {
            display: flex;
            gap: 2rem;
            justify-content: center;
            margin-top: 1.5rem;
        }
      
        .progress-stat {
            text-align: center;
        }
      
        .progress-stat-value {
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--primary);
        }
      
        .progress-stat-label {
            font-size: 0.75rem;
            color: var(--text-tertiary);
            text-transform: uppercase;
            letter-spacing: 0.05em;
        }
      
        /* Mistakes Review Section */
        .mistakes-dashboard {
            margin: 2rem 0;
        }
      
        .mistakes-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 1.5rem;
        }
      
        .mistakes-header h2 {
            font-size: 1.5rem;
            font-weight: 700;
        }
      
        .chapter-weakness-chart {
            background: var(--bg-secondary);
            padding: 1.5rem;
            border-radius: 16px;
            border: 1px solid var(--border);
            margin-bottom: 1.5rem;
        }
      
        .mistakes-list {
            background: var(--bg-secondary);
            border-radius: 16px;
            padding: 1rem;
            border: 1px solid var(--border);
            max-height: 400px;
            overflow-y: auto;
        }
      
        .mistake-item {
            padding: 1rem;
            background: var(--bg-primary);
            border-radius: 12px;
            margin-bottom: 0.75rem;
            border-left: 4px solid var(--danger);
            cursor: pointer;
            transition: all 0.2s ease;
        }
      
        .mistake-item:hover {
            transform: translateX(4px);
            box-shadow: var(--shadow);
        }
      
        .mistake-question {
            font-weight: 600;
            margin-bottom: 0.5rem;
            color: var(--text-primary);
        }
      
        .mistake-details {
            font-size: 0.875rem;
            color: var(--text-secondary);
        }
      
        .mistake-chapter {
            display: inline-block;
            padding: 0.25rem 0.5rem;
            background: var(--bg-tertiary);
            border-radius: 6px;
            font-size: 0.75rem;
            margin-top: 0.5rem;
        }
      
        /* Header */
        .header {
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            height: 70px;
            background: var(--bg-primary);
            border-bottom: 1px solid var(--border);
            display: flex;
            align-items: center;
            justify-content: space-between;
            padding: 0 2rem;
            z-index: 1000;
            box-shadow: var(--shadow-sm);
        }
        .logo {
            font-size: 1.5rem;
            font-weight: 700;
            background: linear-gradient(135deg, var(--primary), var(--primary-light));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }
        .header-actions {
            display: flex;
            align-items: center;
            gap: 1rem;
        }
        .theme-toggle {
            width: 40px;
            height: 40px;
            border-radius: 10px;
            border: none;
            background: var(--bg-secondary);
            color: var(--text-primary);
            cursor: pointer;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.25rem;
            transition: all 0.2s;
        }
        .theme-toggle:hover {
            background: var(--bg-tertiary);
            transform: scale(1.05);
        }
        .user-badge {
            display: flex;
            align-items: center;
            gap: 0.75rem;
            padding: 0.5rem 1rem;
            background: var(--bg-secondary);
            border-radius: 10px;
            font-size: 0.875rem;
        }
        .premium-badge {
            background: linear-gradient(135deg, #fbbf24, #f59e0b);
            color: #000;
            padding: 0.25rem 0.5rem;
            border-radius: 6px;
            font-weight: 600;
            font-size: 0.75rem;
        }
        /* Main Layout */
        .main-container {
            margin-top: 70px;
            min-height: calc(100vh - 70px);
            display: flex;
        }
        /* Sidebar */
        .sidebar {
            width: 280px;
            background: var(--bg-secondary);
            border-right: 1px solid var(--border);
            padding: 1.25rem 1rem;
            overflow-y: auto;
            position: fixed;
            left: 0;
            top: 70px;
            bottom: 0;
        }
        .sidebar-section {
            margin-bottom: 1.5rem;
        }
        .sidebar-title {
            font-size: 0.625rem;
            font-weight: 600;
            text-transform: uppercase;
            letter-spacing: 0.05em;
            color: var(--text-tertiary);
            margin-bottom: 0.75rem;
        }
        .nav-item {
            padding: 0.625rem 0.875rem;
            border-radius: 10px;
            margin-bottom: 0.375rem;
            cursor: pointer;
            transition: all 0.2s;
            display: flex;
            align-items: center;
            gap: 0.625rem;
            color: var(--text-secondary);
            font-weight: 500;
            font-size: 0.9375rem;
        }
        .nav-item:hover {
            background: var(--bg-tertiary);
            color: var(--text-primary);
        }
        .nav-item.active {
            background: var(--primary);
            color: white;
        }
        /* Content Area */
        .content {
            margin-left: 280px;
            flex: 1;
            padding: 1.25rem;
            max-width: 1400px;
        }
        /* Hero */
        .hero {
            text-align: center;
            padding: 2rem;
            max-width: 800px;
            margin: 0 auto;
            transition: all 0.3s ease;
        }
        .hero h1 {
            font-size: 2.5rem;
            font-weight: 800;
            margin-bottom: 0.75rem;
            background: linear-gradient(135deg, var(--primary), var(--primary-light));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
            line-height: 1.2;
        }
        .hero-subtitle {
            font-size: 1.0625rem;
            color: var(--text-secondary);
            margin-bottom: 1.25rem;
            line-height: 1.6;
        }
        .feature-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
            gap: 1rem;
            margin: 2rem 0;
        }
        .feature-card {
            background: var(--bg-secondary);
            padding: 1.5rem;
            border-radius: 16px;
            border: 1px solid var(--border);
            text-align: left;
            transition: all 0.2s ease;
        }
        .feature-card:hover {
            transform: translateY(-2px);
            box-shadow: var(--shadow-lg);
            border-color: var(--primary);
        }
        .feature-icon {
            font-size: 1.5rem;
            margin-bottom: 0.75rem;
        }
        .feature-title {
            font-weight: 600;
            margin-bottom: 0.4375rem;
            font-size: 1rem;
        }
        .feature-desc {
            color: var(--text-secondary);
            font-size: 0.8125rem;
            line-height: 1.5;
        }
        /* Buttons */
        .btn {
            padding: 0.75rem 1.5rem;
            border-radius: 10px;
            border: none;
            font-weight: 600;
            font-size: 0.9375rem;
            cursor: pointer;
            transition: all 0.2s;
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 0.5rem;
            text-decoration: none;
        }
        .btn-primary {
            background: var(--primary);
            color: white;
        }
        .btn-primary:hover:not(:disabled) {
            background: var(--primary-dark);
            transform: translateY(-2px);
            box-shadow: var(--shadow-lg);
        }
        .btn-secondary {
            background: var(--bg-secondary);
            color: var(--text-primary);
            border: 1px solid var(--border);
        }
        .btn-secondary:hover:not(:disabled) {
            background: var(--bg-tertiary);
        }
        .btn-success {
            background: var(--success);
            color: white;
        }
        .btn-danger {
            background: var(--danger);
            color: white;
        }
        .btn-warning {
            background: var(--warning);
            color: white;
        }
   
        .btn-gold {
            background: linear-gradient(135deg, #fbbf24, #f59e0b);
            color: #000;
            font-weight: 700;
        }
   
        .btn-gold:hover:not(:disabled) {
            background: linear-gradient(135deg, #f59e0b, #d97706);
            transform: translateY(-2px);
            box-shadow: 0 10px 25px rgba(251, 191, 36, 0.3);
        }
        .btn:disabled {
            opacity: 0.5;
            cursor: not-allowed;
        }
        .btn-large {
            padding: 1rem 2rem;
            font-size: 1.0625rem;
        }
        /* Quiz Interface */
        .quiz-layout {
            display: grid;
            grid-template-columns: 1fr 280px;
            gap: 1rem;
            height: calc(100vh - 140px);
        }
        .quiz-main {
            background: var(--bg-secondary);
            border-radius: 20px;
            padding: 2.25rem;
            display: flex;
            flex-direction: column;
            border: 1px solid var(--border);
            position: relative;
        }
        .quiz-sidebar {
            display: flex;
            flex-direction: column;
            gap: 0.875rem;
        }
        .progress-card {
            background: var(--bg-secondary);
            border-radius: 16px;
            padding: 1rem;
            border: 1px solid var(--border);
        }
        .progress-header {
            font-size: 0.6875rem;
            color: var(--text-secondary);
            margin-bottom: 0.625rem;
            font-weight: 600;
            text-transform: uppercase;
            letter-spacing: 0.05em;
        }
        .progress-bar-container {
            height: 6px;
            background: var(--border);
            border-radius: 10px;
            overflow: hidden;
            margin-bottom: 0.5rem;
        }
        .progress-bar-fill {
            height: 100%;
            background: linear-gradient(90deg, var(--primary), var(--primary-light));
            transition: width 0.3s ease;
            border-radius: 10px;
        }
        .progress-text {
            font-size: 0.75rem;
            color: var(--text-tertiary);
            font-weight: 500;
        }
        .stats-grid {
            display: grid;
            grid-template-columns: repeat(2, 1fr);
            gap: 0.625rem;
        }
      
        .stats-overview-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 1rem;
            margin-bottom: 2rem;
        }
      
        .stat-box {
            text-align: center;
            padding: 0.75rem;
            background: var(--bg-tertiary);
            border-radius: 10px;
            transition: transform 0.2s ease;
        }
        .stat-box:hover {
            transform: translateY(-2px);
        }
        .stat-value {
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--primary);
            line-height: 1;
            transition: color 0.3s ease;
        }
        .stat-label {
            font-size: 0.625rem;
            color: var(--text-secondary);
            text-transform: uppercase;
            letter-spacing: 0.05em;
            margin-top: 0.3125rem;
        }
        .question-container {
            flex: 1;
            display: flex;
            flex-direction: column;
            position: relative;
        }
        .question-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 1.75rem;
            padding-bottom: 1.125rem;
            border-bottom: 2px solid var(--border);
        }
        .question-number {
            font-size: 1.0625rem;
            font-weight: 700;
            color: var(--primary);
        }
        .question-meta {
            font-size: 0.875rem;
            color: var(--text-tertiary);
            font-weight: 500;
            display: flex;
            align-items: center;
            gap: 0.75rem;
        }
        .report-btn {
            width: 32px;
            height: 32px;
            border-radius: 50%;
            background: var(--danger);
            color: white;
            border: none;
            cursor: pointer;
            font-size: 1rem;
            font-weight: 700;
            display: flex;
            align-items: center;
            justify-content: center;
            transition: all 0.2s ease;
            box-shadow: var(--shadow);
        }
        .report-btn:hover {
            background: #dc2626;
            transform: scale(1.1);
            box-shadow: var(--shadow-lg);
        }
        .report-btn:active {
            transform: scale(0.95);
        }
        .question-text {
            font-size: 1.4375rem;
            font-weight: 600;
            color: var(--text-primary);
            margin-bottom: 1.75rem;
            line-height: 1.6;
            letter-spacing: -0.01em;
        }
        .options-container {
            display: flex;
            flex-direction: column;
            gap: 0.875rem;
            margin-bottom: 1.25rem;
            padding-right: 80px;
        }
        .option {
            padding: 1.125rem 1.375rem;
            background: var(--bg-primary);
            border: 2px solid var(--border);
            border-radius: 12px;
            cursor: pointer;
            transition: all 0.2s;
            font-size: 1.0625rem;
            position: relative;
            line-height: 1.6;
            font-weight: 500;
        }
        .option:hover:not(.locked) {
            border-color: var(--primary);
            transform: translateX(4px);
            box-shadow: var(--shadow);
        }
        .option.selected {
            border-color: var(--primary);
            background: rgba(79, 70, 229, 0.05);
        }
        .option.correct {
            border-color: var(--success);
            background: rgba(16, 185, 129, 0.1);
        }
        .option.incorrect {
            border-color: var(--danger);
            background: rgba(239, 68, 68, 0.1);
        }
        .option.locked {
            cursor: not-allowed;
        }
        .feedback-box {
            padding: 1rem;
            border-radius: 10px;
            margin-top: 1.125rem;
            font-weight: 500;
            display: none;
            font-size: 0.9375rem;
            line-height: 1.5;
        }
        .feedback-box.correct {
            background: rgba(16, 185, 129, 0.1);
            border: 2px solid var(--success);
            color: var(--success);
        }
        .feedback-box.incorrect {
            background: rgba(239, 68, 68, 0.1);
            border: 2px solid var(--danger);
            color: var(--danger);
        }
        .quiz-controls {
            display: flex;
            gap: 0.75rem;
            margin-top: auto;
            padding-top: 1.25rem;
        }
        /* Floating Next Button */
        .floating-next {
            position: absolute;
            right: -70px;
            top: 50%;
            transform: translateY(-50%);
            width: 60px;
            height: 60px;
            border-radius: 50%;
            background: var(--primary);
            color: white;
            border: none;
            cursor: pointer;
            font-size: 1.5rem;
            display: flex;
            align-items: center;
            justify-content: center;
            box-shadow: var(--shadow-lg);
            transition: all 0.3s ease;
            z-index: 10;
        }
        .floating-next:hover:not(:disabled) {
            background: var(--primary-dark);
            transform: translateY(-50%) scale(1.1);
            box-shadow: var(--shadow-xl);
        }
        .floating-next:disabled {
            opacity: 0.4;
            cursor: not-allowed;
            background: var(--text-tertiary);
        }
        .floating-next.answered {
            animation: pulse 0.5s ease;
        }
        @keyframes pulse {
            0%, 100% { transform: translateY(-50%) scale(1); }
            50% { transform: translateY(-50%) scale(1.15); }
        }
        /* Results Page */
        .results-container {
            max-width: 1200px;
            margin: 0 auto;
        }
        .results-header {
            text-align: center;
            margin-bottom: 1.5rem;
        }
        .results-header h1 {
            font-size: 2rem;
            font-weight: 700;
            margin-bottom: 0.5rem;
        }
        .score-summary {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
            gap: 1rem;
            margin-bottom: 2rem;
        }
        .score-card {
            background: var(--bg-secondary);
            padding: 1.25rem;
            border-radius: 16px;
            text-align: center;
            border: 1px solid var(--border);
        }
        .score-card-value {
            font-size: 2.25rem;
            font-weight: 800;
            margin-bottom: 0.375rem;
        }
        .score-card-label {
            color: var(--text-secondary);
            font-size: 0.75rem;
            text-transform: uppercase;
            letter-spacing: 0.05em;
        }
        .charts-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
            gap: 1.25rem;
            margin-bottom: 2rem;
        }
        .chart-card {
            background: var(--bg-secondary);
            padding: 1.25rem;
            border-radius: 16px;
            border: 1px solid var(--border);
            min-height: 260px;
            display: flex;
            flex-direction: column;
        }
        .chart-title {
            font-size: 1rem;
            font-weight: 600;
            margin-bottom: 1rem;
        }
        .chart-empty {
            flex: 1;
            display: flex;
            align-items: center;
            justify-content: center;
            color: var(--text-tertiary);
            font-style: italic;
            font-size: 0.875rem;
            text-align: center;
            padding: 1.5rem;
            background: var(--bg-tertiary);
            border-radius: 12px;
        }
        .review-section {
            background: var(--bg-secondary);
            border-radius: 16px;
            padding: 1.25rem;
            border: 1px solid var(--border);
        }
        .review-item {
            padding: 1rem;
            background: var(--bg-primary);
            border-radius: 12px;
            margin-bottom: 0.75rem;
            border-left: 4px solid var(--danger);
        }
        .review-question {
            font-weight: 600;
            margin-bottom: 0.75rem;
            font-size: 1rem;
        }
        .review-answers {
            display: flex;
            flex-direction: column;
            gap: 0.4375rem;
            font-size: 0.8125rem;
        }
        .review-correct {
            color: var(--success);
        }
        .review-incorrect {
            color: var(--danger);
        }
        /* Pricing */
        .pricing-grid {
            display: grid;
            grid-template-columns: 1fr 1.15fr 1fr;
            gap: 1.5rem;
            margin: 1.5rem auto;
            max-width: 1100px;
            align-items: center;
            justify-items: center;
        }
        .pricing-card {
            background: var(--bg-secondary);
            border: 2px solid var(--border);
            border-radius: 20px;
            padding: 1.75rem 1.5rem;
            text-align: center;
            transition: all 0.3s;
            position: relative;
            display: flex;
            flex-direction: column;
            align-items: center;
            height: 100%;
            width: 100%;
            max-width: 340px;
        }
        .pricing-card.featured {
            border-color: var(--success);
            transform: scale(1.08);
            box-shadow: var(--shadow-xl);
            z-index: 2;
        }
        .pricing-card:hover {
            transform: translateY(-8px);
            box-shadow: var(--shadow-xl);
        }
        .pricing-card.featured {
            border-color: var(--primary);
            transform: scale(1.05);
        }
        .best-value {
            position: absolute;
            top: -12px;
            right: 20px;
            background: var(--success);
            color: white;
            padding: 0.375rem 1rem;
            border-radius: 20px;
            font-size: 0.6875rem;
            font-weight: 700;
            text-transform: uppercase;
            letter-spacing: 0.05em;
            box-shadow: var(--shadow-lg);
        }
        .pricing-name {
            font-size: 1.375rem;
            font-weight: 700;
            margin-bottom: 0.625rem;
        }
        .pricing-price {
            font-size: 2.5rem;
            font-weight: 800;
            color: var(--primary);
            margin: 0.625rem 0 0.5rem;
        }
        .pricing-price small {
            font-size: 0.875rem;
            color: var(--text-secondary);
        }
        .pricing-total {
            color: var(--text-secondary);
            font-size: 0.9375rem;
            margin-bottom: 1.125rem;
            font-weight: 500;
            padding: 0.3125rem 0.875rem;
            background: var(--bg-tertiary);
            border-radius: 8px;
            display: inline-block;
        }
        .pricing-features {
            list-style: none;
            margin: 1.125rem 0 1.375rem;
            text-align: left;
            width: 100%;
        }
        .pricing-features li {
            padding: 0.5rem 0;
            border-bottom: 1px solid var(--border);
            color: var(--text-secondary);
            font-size: 0.9375rem;
        }
        .pricing-features li:last-child {
            border-bottom: none;
        }
        .pricing-features li::before {
            content: "✓";
            color: var(--success);
            font-weight: bold;
            margin-right: 0.75rem;
        }
        /* Modal */
        .modal-overlay {
            position: fixed;
            inset: 0;
            background: rgba(0, 0, 0, 0.7);
            display: none;
            align-items: center;
            justify-content: center;
            z-index: 2000;
            backdrop-filter: blur(4px);
        }
        .modal {
            background: var(--bg-primary);
            border-radius: 20px;
            padding: 3rem;
            max-width: 500px;
            width: 90%;
            box-shadow: var(--shadow-xl);
            position: relative;
        }
        .auth-loading-overlay {
            position: absolute;
            inset: 0;
            background: rgba(0, 0, 0, 0.92);
            backdrop-filter: blur(12px);
            border-radius: 20px;
            display: none;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            z-index: 10;
            animation: fadeIn 0.3s ease;
        }
        .auth-loading-overlay.active {
            display: flex;
        }

        /* Modern Single Gradient Spinner - CLEAN & MINIMAL */
.auth-spinner {
    position: relative;
    width: 60px;
    height: 60px;
    margin-bottom: 2rem;
}

.auth-spinner::before {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: 50%;
    border: 3px solid rgba(99, 102, 241, 0.1);
    border-top-color: var(--primary);
    animation: cleanSpin 1s linear infinite;
}

@keyframes cleanSpin {
    to { transform: rotate(360deg); }
}
        .modal h2 {
            margin-bottom: 1.5rem;
            font-size: 1.875rem;
        }
        .form-group {
            margin-bottom: 1.5rem;
        }
        .form-label {
            display: block;
            margin-bottom: 0.5rem;
            font-weight: 500;
            color: var(--text-secondary);
            font-size: 1rem;
        }
        .form-input {
            width: 100%;
            padding: 1rem;
            border: 2px solid var(--border);
            border-radius: 10px;
            background: var(--bg-secondary);
            color: var(--text-primary);
            font-size: 1.125rem;
            transition: all 0.2s;
        }
        .form-input:focus {
            outline: none;
            border-color: var(--primary);
        }
        .error-message {
            background: rgba(239, 68, 68, 0.1);
            color: var(--danger);
            padding: 1rem;
            border-radius: 10px;
            margin-bottom: 1rem;
            display: none;
        }
        /* Notification */
        .notification {
            position: fixed;
            top: 90px;
            right: 2rem;
            padding: 1rem 1.5rem;
            border-radius: 10px;
            background: var(--primary);
            color: white;
            box-shadow: var(--shadow-xl);
            z-index: 3000;
            animation: slideIn 0.3s ease;
        }
        @keyframes slideIn {
            from {
                transform: translateX(400px);
                opacity: 0;
            }
            to {
                transform: translateX(0);
                opacity: 1;
            }
        }
        /* Loading */
        .loading-spinner {
            border: 3px solid var(--border);
            border-top: 3px solid var(--primary);
            border-radius: 50%;
            width: 40px;
            height: 40px;
            animation: spin 1s linear infinite;
            margin: 2rem auto;
        }
        @keyframes spin {
            to { transform: rotate(360deg); }
        }
        /* Responsive */
        @media (max-width: 1024px) {
            .sidebar {
                transform: translateX(-100%);
                transition: transform 0.3s ease;
                z-index: 999;
            }
          
            .sidebar.mobile-open {
                transform: translateX(0);
            }
         
            .content {
                margin-left: 0;
                padding: 1rem;
            }
            .quiz-layout {
                grid-template-columns: 1fr;
            }
            .quiz-sidebar {
                order: -1;
                flex-direction: row;
                gap: 0.75rem;
                overflow-x: auto;
                margin-bottom: 1rem;
            }
            .floating-next {
                display: none;
            }
            .options-container {
                padding-right: 0;
            }
            .stats-overview-grid {
                grid-template-columns: repeat(2, 1fr);
            }
        }
      
        @media (max-width: 768px) {
            .header {
                padding: 0 1rem;
            }
          
            .logo {
                font-size: 1.25rem;
            }
          
            .hero h1 {
                font-size: 1.75rem;
            }
          
            .welcome-text {
                font-size: 1.5rem;
            }
          
            .progress-ring {
                width: 160px;
                height: 160px;
            }
          
            .progress-ring svg {
                width: 160px;
                height: 160px;
            }
          
            .progress-ring-circle,
            .progress-ring-progress {
                cx: 80;
                cy: 80;
                r: 74;
            }
          
            .progress-percentage {
                font-size: 2rem;
            }
          
            .progress-stats {
                flex-direction: column;
                gap: 1rem;
            }
          
            .charts-grid {
                grid-template-columns: 1fr;
            }
          
            .quiz-main {
                padding: 1.25rem;
                border-radius: 16px;
            }
          
            .question-text {
                font-size: 1.125rem;
                margin-bottom: 1.5rem;
            }
          
            .option {
                font-size: 0.9375rem;
                padding: 1rem 1.25rem;
            }
          
            .quiz-controls {
                flex-wrap: wrap;
            }
          
            .quiz-controls .btn {
                flex: 1;
                min-width: 100px;
            }
          
            .stats-overview-grid {
                grid-template-columns: 1fr;
                gap: 0.75rem;
            }
          
            .score-card {
                padding: 1rem;
            }
          
            .score-card-value {
                font-size: 1.875rem;
            }
          
            .pricing-grid {
                grid-template-columns: 1fr;
            }
          
            .pricing-card {
                max-width: 100%;
            }
          
            .pricing-card.featured {
                transform: scale(1);
                order: -1;
            }
          
            .form-input {
                font-size: 1rem;
                padding: 0.875rem;
            }
          
            .mistake-item {
                font-size: 0.875rem;
            }
          
            .feature-grid {
                grid-template-columns: 1fr;
            }
          
            .mistakes-header {
                flex-direction: column;
                gap: 1rem;
            }
          
            .mistakes-header div {
                flex-direction: column;
                width: 100%;
            }
          
            .mistakes-header .btn {
                width: 100%;
            }
          
            .mobile-menu-toggle {
                display: block;
                position: fixed;
                bottom: 20px;
                right: 20px;
                width: 56px;
                height: 56px;
                border-radius: 50%;
                background: var(--primary);
                color: white;
                border: none;
                box-shadow: var(--shadow-xl);
                z-index: 1001;
                font-size: 1.5rem;
                display: flex;
                align-items: center;
                justify-content: center;
            }
          
            .modal {
                padding: 2rem;
                width: 95%;
            }
          
            .auth-spinner {
                width: 50px;
                height: 50px;
            }
          
            .auth-loading-text {
                font-size: 1rem;
                padding: 0 1rem;
            }
          
            .auth-spinner {
                width: 50px;
                height: 50px;
            }
          
            .auth-loading-text {
                font-size: 1rem;
                padding: 0 1rem;
            }
        }
      
        @media (max-width: 480px) {
            .hero {
                padding: 1rem;
            }
          
            .welcome-text {
                font-size: 1.25rem;
            }
          
            .progress-ring {
                width: 140px;
                height: 140px;
            }
          
            .progress-ring svg {
                width: 140px;
                height: 140px;
            }
          
            .progress-percentage {
                font-size: 1.75rem;
            }
          
            .question-text {
                font-size: 1rem;
            }
          
            .option {
                font-size: 0.875rem;
                padding: 0.875rem 1rem;
            }
          
            .quiz-controls {
                gap: 0.5rem;
            }
          
            .quiz-controls .btn {
                font-size: 0.875rem;
                padding: 0.625rem 1rem;
            }
          
            .chart-card {
                min-height: 220px;
            }
          
            .notification {
                right: 1rem;
                left: 1rem;
                width: auto;
            }
        }
      
        .mobile-menu-toggle {
            display: none;
        }
      
        @media (max-width: 768px) {
            .mobile-menu-toggle {
                display: flex;
            }
        }
        .hidden {
            display: none !important;
        }