:root{--lesson-font-scale: 1;--font-mono: "JetBrains Mono", "Consolas", "Monaco", "Courier New", "Noto Sans Mono", monospace;--font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans", sans-serif}.student-container{min-height:100vh;background:#f8fafc;padding:20px}.login-card,.topic-card,.complete-card{max-width:600px;margin:60px auto;background:#fff;padding:40px;border-radius:4px;border:1px solid #E2E8F0}.login-card h1,.topic-card h2,.complete-card h1{text-align:center;margin-bottom:32px;color:var(--text-primary)}.lesson-header{background:#fff;padding:24px;border-radius:4px;margin-bottom:20px;border:1px solid #E2E8F0}.lesson-info{display:flex;justify-content:space-between;align-items:center;margin-bottom:16px;flex-wrap:wrap;gap:12px}.lesson-info h2{font-size:1.5rem;color:var(--text-primary)}.header-controls{display:flex;align-items:center;gap:20px;flex-wrap:wrap}.font-size-control{display:flex;align-items:center;gap:8px;background:var(--bg-alt);padding:4px 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.progress-text{position:absolute;top:50%;left:50%;transform:translate(-50%,-50%);font-size:.75rem;font-weight:700;color:var(--text-primary)}.progress-ring.milestone .progress-ring-fill{animation:ring-pulse .6s ease-out}@keyframes ring-pulse{0%{stroke-width:4}50%{stroke-width:6;stroke:#059669}to{stroke-width:4}}.progress-indicator.completed .progress-ring-fill{stroke:#10b981}.progress-indicator.completed:after{content:"✓";position:absolute;top:50%;left:50%;transform:translate(-50%,-50%);font-size:1rem;color:#10b981;animation:check-pop .4s ease-out}.progress-indicator.completed .progress-text{opacity:0}@keyframes check-pop{0%{transform:translate(-50%,-50%) scale(0)}50%{transform:translate(-50%,-50%) scale(1.3)}to{transform:translate(-50%,-50%) scale(1)}}.virtual-teacher{background:#fff;padding:24px;border-radius:4px;margin-bottom:20px;border:1px solid #E2E8F0;display:flex;align-items:flex-start;gap:16px}.teacher-avatar{font-size:2.5rem;flex-shrink:0}.teacher-message{flex:1;padding:16px;background:var(--bg-alt);border-radius:4px;font-size:calc(1.1rem * var(--lesson-font-scale));line-height:1.7;color:var(--text-primary)}.lesson-content{display:flex;flex-direction:column;gap:20px}.content-area{background:#fff;padding:32px;border-radius:4px;margin-bottom:20px;border:1px solid #E2E8F0;min-height:300px;font-size:calc(1.1rem * var(--lesson-font-scale));line-height:1.7}.explanation-block{font-size:calc(1.15rem * var(--lesson-font-scale));line-height:1.8}.explanation-text{margin-bottom:24px}.explanation-text code{background:var(--bg-alt);padding:2px 8px;border-radius:4px;font-family:var(--font-mono);font-size:.95em}.code-example{margin-top:20px}.code-example pre{background:#1e293b;color:#e2e8f0;padding:20px;border-radius:4px;overflow-x:auto;font-size:.95rem;line-height:1.6}.code-block{background:#1e293b;color:#e2e8f0;padding:16px 20px;border-radius:4px;overflow-x:auto;font-size:.9rem;line-height:1.6;margin:16px 0;white-space:pre;font-family:var(--font-mono);tab-size:4}.explanation-text .code-block code,.code-block code{background:transparent!important;padding:0;color:inherit;font-family:var(--font-mono);border:none;box-shadow:none}.diagram-container{margin:24px 0;padding:20px;background:var(--bg-alt);border-radius:4px;border:1px solid var(--border);text-align:center}.diagram-caption{margin-top:12px;font-size:.9rem;color:var(--text-secondary);font-style:italic}.diagram-loading{display:flex;justify-content:center;align-items:center;min-height:100px;color:var(--text-secondary);font-style:italic}.diagram-loading:before{content:"";width:20px;height:20px;border:2px solid var(--border);border-top-color:var(--primary);border-radius:4px;margin-right:10px;animation:diagram-spin .8s linear infinite}@keyframes diagram-spin{to{transform:rotate(360deg)}}.embedded-media{margin:20px 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line{vector-effect:non-scaling-stroke}.chart-diagram{max-width:100%;max-height:350px}.function-plot-diagram{display:flex;justify-content:center;overflow-x:auto}.function-plot-diagram svg{max-width:100%}.physics-diagram{display:flex;justify-content:center;align-items:center}.physics-diagram svg{max-width:100%;height:auto;min-height:150px;max-height:350px}.mermaid-diagram{display:flex;justify-content:center;align-items:center;min-height:100px;overflow-x:auto}.mermaid-diagram svg{max-width:100%;max-height:40vh;height:auto}.ascii-diagram{font-family:var(--font-mono);font-size:.95rem;line-height:1.4;background:#1e293b;color:#e2e8f0;padding:20px;border-radius:4px;text-align:left;display:inline-block;white-space:pre;overflow-x:auto;max-width:100%}.diagram-description{background:#f8fafc;border:1px solid #bae6fd;border-radius:4px;padding:20px;text-align:left;margin:16px auto;max-width:600px}.diagram-description .description-content{display:flex;gap:12px;align-items:flex-start}.diagram-description .description-icon{font-size:1.5rem;flex-shrink:0}.diagram-description .description-content p{margin:0;line-height:1.7;color:#0c4a6e;font-size:1rem}.diagram-container .force-arrow{stroke-width:3}.diagram-container .object{fill:#e2e8f0;stroke:#64748b;stroke-width:2}.diagram-container .label{font-size:14px;font-weight:500}.diagram-hint{display:flex;align-items:center;justify-content:center;gap:8px;margin-top:8px;padding:8px 16px;background:#eff6ff;border-radius:4px;font-size:.85rem;color:#1e40af}.diagram-hint:before{content:"💡"}@media(max-width:600px){.diagram-container{padding:12px;margin:16px 0}.svg-diagram svg{min-height:120px;max-height:300px}.ascii-diagram{font-size:.8rem;padding:12px}}.explanation-text{font-size:calc(1.15rem * var(--lesson-font-scale));line-height:1.8}.explanation-text p{margin-bottom:16px}.explanation-text h3{font-size:calc(1.3rem * var(--lesson-font-scale));margin:20px 0 12px;color:var(--text-primary)}.explanation-text ul{margin:12px 0;padding-left:24px}.explanation-text li{margin-bottom:8px}.explanation-text code{background:#f1f5f9;padding:2px 6px;border-radius:4px;font-family:var(--font-mono);font-size:.9em;color:#0f172a}.mcq-container .question-text{font-size:calc(1.2rem * var(--lesson-font-scale));margin-bottom:24px;font-weight:500}.options-list{display:flex;flex-direction:column;gap:12px}.option-btn{display:flex;align-items:flex-start;gap:16px;padding:16px 20px;border:2px solid var(--border);border-radius:4px;background:#fff;cursor:pointer;transition:var(--transition);text-align:left;font-size:calc(1.1rem * var(--lesson-font-scale));width:100%}.option-btn .option-letter{margin-top:4px}.option-btn:hover{border-color:var(--primary);background:var(--bg-alt)}.option-btn.selected{border-color:var(--primary);background:#eff6ff}.option-letter{display:flex;align-items:center;justify-content:center;width:32px;height:32px;background:var(--primary);color:#fff;border-radius:4px;font-weight:600;flex-shrink:0}.option-text{flex:1;font-size:calc(1.1rem * var(--lesson-font-scale));line-height:1.5}.option-table{border-collapse:collapse;font-size:calc(.95rem * var(--lesson-font-scale));background:#f8fafc;border-radius:6px;overflow:hidden;margin:4px 0}.option-table th,.option-table td{padding:8px 16px;text-align:center;border:1px solid #e2e8f0}.option-table th{background:#e2e8f0;font-weight:600;color:#334155}.option-table td{background:#fff}.option-table tr:nth-child(2n) td{background:#f8fafc}.option-btn:hover .option-table th{background:#cbd5e1}.option-btn.selected .option-table th{background:#bfdbfe}.option-btn.selected .option-table td{background:#eff6ff}.option-btn.selected .option-table tr:nth-child(2n) td{background:#dbeafe}.short-answer-container .question-text{font-size:calc(1.2rem * var(--lesson-font-scale));margin-bottom:20px;font-weight:500}.answer-input{font-family:inherit;font-size:calc(1.1rem * var(--lesson-font-scale));line-height:1.6}.code-editor{font-family:var(--font-mono);font-size:calc(1rem * var(--lesson-font-scale));line-height:1.5;background:#1e293b;color:#e2e8f0;border:2px solid #334155;border-radius:4px;padding:16px;width:100%;min-height:150px;resize:vertical;tab-size:4;-moz-tab-size:4;white-space:pre-wrap;word-wrap:break-word}.code-editor:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 3px #2563eb33}.code-editor::placeholder{color:#64748b}.code-fill-container{margin:16px 0;border-radius:4px;overflow:hidden;border:1px solid #334155;background:#1e293b}.code-header{display:flex;justify-content:space-between;align-items:center;padding:8px 16px;background:#0f172a;border-bottom:1px solid #334155}.code-header-small{background:#0f172a;color:#64748b;font-size:.75rem;padding:4px 12px;border-radius:4px 4px 0 0;border-bottom:1px solid #334155;text-transform:uppercase;font-weight:600;width:fit-content}.code-example .code-block{margin-top:0;border-top-left-radius:0}.code-language-badge{background:#3b82f6;color:#fff;padding:2px 10px;border-radius:4px;font-size:.75rem;font-weight:600;text-transform:uppercase;letter-spacing:.5px}.code-hint{color:#94a3b8;font-size:.85rem}.code-editor-wrapper{display:flex;overflow-x:auto}.line-numbers{display:flex;flex-direction:column;padding:16px 0;background:#0f172a;border-right:1px solid #334155;text-align:right;-webkit-user-select:none;user-select:none;min-width:40px}.line-numbers span{padding:0 12px;color:#64748b;font-family:var(--font-mono);font-size:.85rem;line-height:1.8}.code-template{flex:1;background:#1e293b;color:#e2e8f0;font-family:var(--font-mono);font-size:calc(1rem * var(--lesson-font-scale));line-height:1.8;margin:0;padding:16px 20px;white-space:pre-wrap;overflow-x:auto;tab-size:4}.syntax-keyword{color:#c792ea;font-weight:500}.syntax-string{color:#c3e88d}.syntax-comment{color:#676e95;font-style:italic}.syntax-function{color:#82aaff}.syntax-number{color:#f78c6c}.syntax-attribute{color:#ffcb6b}.blank-wrapper{position:relative;display:inline-block}.code-blank{background:#0f172a;border:2px solid #60a5fa;border-radius:4px;padding:4px 12px;font-family:var(--font-mono);font-size:calc(1rem * var(--lesson-font-scale));min-width:80px;color:#fbbf24;transition:all .2s ease;vertical-align:baseline;margin:0 2px}.code-blank:focus{outline:none;border-color:#34d399;box-shadow:0 0 0 3px #34d3994d;background:#1e293b}.code-blank.blank-correct{border-color:#34d399;background:#34d3991a}.code-template input,.code-template .code-blank,pre input[type=text]{position:relative;z-index:10;pointer-events:auto!important;-webkit-user-select:text;user-select:text;cursor:text}.blank-number{position:absolute;top:-8px;right:-8px;background:#3b82f6;color:#fff;width:18px;height:18px;border-radius:4px;font-size:.7rem;display:flex;align-items:center;justify-content:center;font-weight:600}.code-shortcuts-hint{display:flex;gap:20px;padding:8px 16px;background:#f8fafc;border-top:1px solid var(--border);font-size:.8rem;color:#64748b}.interaction-area{background:#fff;padding:24px;border-radius:4px;border:1px solid var(--border)}.feedback-area{min-height:60px;margin-bottom:16px}.feedback{padding:16px 20px;border-radius:4px;font-size:calc(1.1rem * var(--lesson-font-scale));line-height:1.6;animation:fadeIn .3s ease}.feedback.success{background:#f0fdf4;border:2px solid #bbf7d0;color:#166534}.feedback.error{background:#fef2f2;border:2px solid #fecaca;color:#991b1b}.feedback.info{background:#eff6ff;border:2px solid #bfdbfe;color:#1e40af}.feedback.warning{background:#fffbeb;border:2px solid #fde68a;color:#92400e}.controls-area{display:flex;gap:12px;justify-content:space-between;align-items:center}.controls-left,.controls-right{display:flex;gap:12px;align-items:center}.btn-tutor{background:var(--primary);color:#fff;border:1px solid var(--primary-dark);padding:10px 16px;border-radius:4px;font-weight:500;cursor:pointer;transition:all .15s ease}.btn-tutor:hover,.btn-tutor.active{background:var(--primary-dark)}.btn-tutor.tutor-btn-highlight{animation:tutor-pulse 1.5s ease-in-out infinite}@keyframes tutor-pulse{0%{transform:scale(1);opacity:1}50%{transform:scale(1.03);opacity:.9}to{transform:scale(1);opacity:1}}.celebration{font-size:5rem;text-align:center;margin-bottom:24px;animation:bounce 1s ease infinite}@keyframes bounce{0%,to{transform:translateY(0)}50%{transform:translateY(-20px)}}.lesson-complete-summary{text-align:center}.encouragement{margin-bottom:32px}.encouragement-emoji{font-size:4rem;display:block;margin-bottom:16px}.encouragement-message{font-size:1.25rem;color:var(--text-primary);font-weight:500}.summary-stats{display:grid;grid-template-columns:repeat(3,1fr);gap:20px;margin:32px 0}.stat{text-align:center;padding:20px;background:var(--bg-alt);border-radius:4px}.stat-value{font-size:2.5rem;font-weight:700;color:var(--primary);margin-bottom:8px}.stat-value .stat-unit{font-size:1rem;font-weight:400;color:var(--text-secondary)}.stat-label{color:var(--text-secondary);font-size:.9rem}.concepts-practiced{margin:32px 0;padding:24px;background:var(--bg-alt);border-radius:4px}.concepts-practiced h3{font-size:1rem;color:var(--text-secondary);margin-bottom:16px;font-weight:500}.concept-tags{display:flex;flex-wrap:wrap;gap:10px;justify-content:center}.concept-tag{background:#fff;color:var(--primary);padding:8px 16px;border-radius:4px;font-size:.9rem;font-weight:500;border:1px solid var(--border)}.mastery-section{margin-top:24px}.mastery-toggle{width:100%;padding:16px 20px;background:var(--bg-alt);border:1px solid var(--border);border-radius:4px;cursor:pointer;display:flex;justify-content:space-between;align-items:center;font-size:1rem;color:var(--text-primary);transition:var(--transition)}.mastery-toggle:hover{background:#f1f5f9}.toggle-icon{font-size:.8rem;color:var(--text-secondary)}.mastery-details{margin-top:16px;padding:20px;background:#fff;border:1px solid var(--border);border-radius:4px}.mastery-details.hidden{display:none}.no-mastery{color:var(--text-secondary);text-align:center;padding:20px}.mastery-display{margin:32px 0}.mastery-item{display:grid;grid-template-columns:1fr 2fr auto;align-items:center;gap:16px;padding:12px;margin-bottom:12px;border-radius:4px;background:var(--bg-alt)}.concept-name{font-weight:500}.mastery-bar{height:12px;background:#e5e7eb;border-radius:4px;overflow:hidden}.mastery-fill{height:100%;transition:width .5s ease;border-radius:4px}.mastery-item.strong .mastery-fill{background:#10b981}.mastery-item.okay .mastery-fill{background:#f59e0b}.mastery-item.needs-work .mastery-fill{background:#ef4444}.mastery-percentage{font-weight:600;min-width:48px;text-align:right}.action-buttons{display:flex;gap:16px;justify-content:center;margin-top:32px}@media(max-width:768px){.student-container{padding:12px}.login-card,.topic-card,.complete-card{padding:24px;margin:30px auto}.lesson-header,.virtual-teacher,.content-area,.interaction-area{padding:16px}.lesson-info{flex-direction:column;align-items:flex-start;gap:12px}.controls-area{flex-direction:column;gap:12px}.controls-left{width:100%;flex-direction:column}.controls-right,.controls-area .btn,.controls-left .btn,.controls-right .btn{width:100%}.summary-stats{grid-template-columns:1fr}.action-buttons{flex-direction:column}.action-buttons .btn{width:100%}.mastery-item{grid-template-columns:1fr;gap:8px}}.btn-outline,#back-btn{background:#fff;color:var(--text-secondary, #64748b);border:1px solid var(--border, #e2e8f0);padding:10px 16px;border-radius:4px;cursor:pointer;transition:all .2s ease}.btn-outline:hover,#back-btn:hover{background:var(--surface, #f8fafc);color:var(--text-primary, #1e293b);border-color:var(--text-secondary, #94a3b8)}.math-input-tools{margin-top:16px;display:flex;flex-direction:column;gap:12px}.symbol-tabs{display:flex;gap:4px;flex-wrap:wrap}.symbol-tab{padding:6px 12px;background:var(--bg-alt, #f5f5f5);border:1px solid var(--border, #e0e0e0);border-radius:6px;cursor:pointer;font-size:.85rem;transition:all .15s ease;color:var(--text, #333)}.symbol-tab:hover{background:var(--border, #e0e0e0)}.symbol-tab.active{background:var(--primary, #6366f1);color:#fff;border-color:var(--primary, #6366f1)}.symbol-palette{display:flex;flex-wrap:wrap;gap:6px}.symbol-palette.hidden{display:none!important}.symbol-btn{width:36px;height:36px;border:1px solid var(--border);border-radius:6px;background:#fff;font-size:1.1rem;cursor:pointer;transition:var(--transition);display:flex;align-items:center;justify-content:center}.symbol-btn:hover{background:var(--bg-alt);border-color:var(--primary)}.symbol-btn.fraction-btn{width:auto;padding:0 12px;font-size:.9rem;font-weight:500}.scratchpad-btn{padding:10px 20px;background:var(--primary);color:#fff;border:none;border-radius:4px;font-size:.95rem;cursor:pointer;transition:var(--transition);white-space:nowrap}.scratchpad-btn:hover{background:var(--primary-dark)}.scratchpad-modal{position:fixed;top:0;left:0;width:100%;height:100%;background:#000000b3;display:flex;align-items:center;justify-content:center;z-index:2000;padding:20px}.scratchpad-content{background:#fff;border-radius:4px;max-width:700px;width:100%;max-height:90vh;overflow-y:auto;border:1px solid var(--border)}.scratchpad-header{display:flex;justify-content:space-between;align-items:center;padding:20px 24px;border-bottom:1px solid var(--border)}.scratchpad-header h3{font-size:1.25rem;color:var(--text-primary);margin:0}.close-btn{width:36px;height:36px;border:none;background:var(--bg-alt);border-radius:4px;font-size:1.5rem;cursor:pointer;display:flex;align-items:center;justify-content:center;color:var(--text-secondary);transition:var(--transition)}.close-btn:hover{background:#fee2e2;color:#991b1b}.scratchpad-tools{display:flex;justify-content:space-between;padding:16px 24px;background:var(--bg-alt);border-bottom:1px solid var(--border)}.tool-group{display:flex;gap:8px;align-items:center}.tool-btn{width:40px;height:40px;border:1px solid var(--border);border-radius:4px;background:#fff;font-size:1.2rem;cursor:pointer;transition:var(--transition)}.tool-btn:hover{background:var(--bg-alt);border-color:var(--primary)}.tool-btn.active{background:var(--primary);border-color:var(--primary)}#pen-color{width:40px;height:40px;border:1px solid var(--border);border-radius:4px;cursor:pointer;padding:2px}.canvas-container{padding:20px;background:#fff}#scratchpad-canvas{width:100%;border:2px solid var(--border);border-radius:4px;background:#fff;cursor:crosshair;touch-action:none}.scratchpad-actions{padding:16px 24px;border-top:1px solid var(--border);display:flex;flex-direction:column;gap:12px}.scratchpad-status{min-height:24px;font-size:.95rem}.recognition-result{color:var(--success)}.scratchpad-actions .action-buttons{display:flex;gap:12px;justify-content:flex-end}.scratchpad-hint{padding:12px 24px 20px;font-size:.85rem;color:var(--text-secondary);text-align:center;margin:0}@media(max-width:600px){.scratchpad-modal{padding:10px}.scratchpad-content{max-height:95vh}.scratchpad-tools{flex-direction:column;gap:12px}.math-input-tools{flex-direction:column;align-items:stretch}.symbol-palette{justify-content:center}.scratchpad-btn{width:100%}.scratchpad-actions .action-buttons{flex-direction:column}.scratchpad-actions .btn{width:100%}}.resume-modal{position:fixed;inset:0;background:#000000b3;display:flex;align-items:center;justify-content:center;z-index:10000;animation:fadeIn .3s ease}.resume-modal-content{background:#fff;border-radius:4px;padding:32px;max-width:420px;width:90%;text-align:center;border:1px solid var(--border);position:relative}.modal-close-btn{position:absolute;top:12px;right:12px;background:none;border:none;font-size:1.25rem;color:var(--text-secondary, #64748b);cursor:pointer;padding:4px 8px;border-radius:6px;transition:all .2s ease}.modal-close-btn:hover{background:var(--surface, #f1f5f9);color:var(--text-primary, #1e293b)}.resume-modal-content h2{margin:0 0 16px;font-size:1.5rem;color:var(--text-primary, #1e293b)}.resume-modal-content p{margin:0 0 16px;color:var(--text-secondary, #64748b)}.resume-lesson-info{background:var(--surface, #f8fafc);border-radius:4px;padding:16px;margin-bottom:24px;display:flex;flex-direction:column;gap:8px}.resume-lesson-info strong{font-size:1.1rem;color:var(--text-primary, #1e293b)}.resume-progress{color:var(--primary, #4f46e5);font-weight:600}.resume-progress.completed{color:#166534;background:#dcfce7;padding:4px 12px;border-radius:4px}.resume-date{font-size:.9rem;color:var(--text-secondary, #64748b)}.resume-buttons{display:flex;flex-direction:column;gap:12px}.resume-buttons .btn{padding:14px 20px;border-radius:4px;font-size:1rem;font-weight:600;cursor:pointer;transition:all .2s ease}.resume-buttons .btn-primary{background:var(--primary, #4f46e5);color:#fff;border:none}.resume-buttons .btn-primary:hover{background:var(--primary-dark, #4338ca);transform:translateY(-2px)}.resume-buttons .btn-outline{background:#fff;color:var(--text-secondary, #64748b);border:1px solid var(--border, #e2e8f0)}.resume-buttons .btn-outline:hover{background:var(--surface, #f8fafc);color:var(--text-primary, #1e293b);border-color:var(--text-secondary, #94a3b8)}.resume-secondary-action{margin-top:20px;padding-top:16px;border-top:1px solid var(--border, #e2e8f0)}.resume-secondary-action a{font-size:.85rem;color:var(--text-secondary, #94a3b8);text-decoration:none}.resume-secondary-action a:hover{color:var(--error, #ef4444);text-decoration:underline}.lesson-tabs{display:flex;gap:8px;margin-bottom:24px;border-bottom:2px solid #e2e8f0;padding-bottom:0}.tab-btn{flex:1;padding:14px 20px;background:transparent;border:none;border-bottom:3px solid transparent;font-size:1rem;font-weight:500;color:#64748b;cursor:pointer;transition:all .2s ease;display:flex;align-items:center;justify-content:center;gap:8px;margin-bottom:-2px}.tab-btn:hover{color:#1e293b;background:#f8fafc}.tab-btn.active{color:var(--primary, #4f46e5);border-bottom-color:var(--primary, #4f46e5);background:transparent}.tab-badge{background:var(--primary, #4f46e5);color:#fff;font-size:.75rem;font-weight:600;padding:2px 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8px;border-radius:4px;font-weight:600;margin-left:auto}.lesson-status-badge.completed{background:#dcfce7;color:#166534}.lesson-status-badge.in-progress{background:#fef3c7;color:#92400e}.assigned-lesson-card.completed{border-color:#86efac;background:#f0fdf4}.assigned-lesson-card.completed:hover{border-color:#22c55e;background:#dcfce7}.lesson-card-title{font-size:1.1rem;font-weight:600;color:#1e293b;margin:0;line-height:1.4;flex:1}.lesson-card-meta{display:flex;gap:16px;font-size:.85rem;color:#64748b}.btn-start-lesson{margin-top:auto;width:100%}@media(max-width:600px){.lesson-tabs{gap:4px}.tab-btn{padding:12px;font-size:.9rem}.lessons-grid{grid-template-columns:1fr}.assigned-lesson-card{padding:16px}}.streaming-status{display:flex;align-items:center;gap:10px}.pulse-dot{width:10px;height:10px;background:var(--primary, #4f46e5);border-radius:4px;animation:pulse 1.5s ease-in-out infinite}@keyframes 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.2s}.challenge-accept-btn:hover{transform:translateY(-2px);box-shadow:0 4px 12px #f59e0b66}.challenge-skip-btn{background:transparent;color:#92400e;border:1px solid #d97706;padding:10px 20px;font-size:.95rem;border-radius:8px;cursor:pointer;transition:background .2s}.challenge-skip-btn:hover{background:#d977061a}@keyframes bounce{0%,to{transform:translateY(0)}50%{transform:translateY(-8px)}}@keyframes pulse{0%,to{box-shadow:0 0 #f59e0b4d}50%{box-shadow:0 0 0 8px #f59e0b00}}@media(max-width:480px){.challenge-transition{padding:16px}.challenge-icon{font-size:2.5rem}.challenge-accept-btn{padding:12px 20px;font-size:1rem}}#progress-tab{padding:0}.progress-stats-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:16px;margin-bottom:24px}.stat-card{background:#fff;border:1px solid var(--border);border-radius:4px;padding:20px 16px;text-align:center;transition:border-color .15s}.stat-card:hover{border-color:var(--primary)}.stat-icon{font-size:1.5rem;margin-bottom:8px}.stat-value{font-size:1.75rem;font-weight:700;color:#1e293b;line-height:1.2}.stat-label{font-size:.8rem;color:#64748b;margin-top:4px}.progress-section{background:#fff;border:1px solid #e2e8f0;border-radius:4px;padding:20px;margin-bottom:20px}.progress-section h3{font-size:1.1rem;color:#1e293b;margin:0 0 16px;display:flex;align-items:center;gap:8px}.section-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:16px}.section-header h3{margin:0}.mastery-chart-container{height:250px;margin-bottom:20px}.empty-chart-message,.empty-list-message{text-align:center;color:#64748b;padding:40px 20px;font-style:italic}.mastery-list{display:flex;flex-direction:column;gap:8px}.mastery-list-item{display:flex;align-items:center;gap:12px;padding:12px 16px;background:#f8fafc;border-radius:4px;border-left:4px solid 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.mastery-list-bar{background:#ef4444}.mastery-list-percentage{font-weight:600;font-size:.9rem;color:#475569;min-width:40px;text-align:right}.lesson-history-list{display:flex;flex-direction:column;gap:8px}.history-item{display:flex;align-items:center;gap:16px;padding:14px 16px;background:#f8fafc;border-radius:4px;border:1px solid #e2e8f0}.history-item.completed{border-left:4px solid #22c55e}.history-item.in-progress{border-left:4px solid #f59e0b}.history-item-main{flex:1;min-width:0}.history-item-topic{font-weight:500;color:#1e293b;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;margin-bottom:4px}.history-item-meta{display:flex;gap:12px;font-size:.8rem;color:#64748b}.history-item-stats{display:flex;align-items:center;gap:12px}.history-item-score{font-weight:600;font-size:1.1rem;color:#1e293b}.history-item-status{font-size:.75rem;padding:4px 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.skill-summary-count{color:#16a34a}.skill-summary-label{font-size:.85rem;color:#64748b;font-weight:500}.skill-summary-action{margin-top:10px;font-size:.8rem;padding:6px 12px;border-radius:6px;background:#fff;border:none;cursor:pointer;font-weight:500;transition:background .2s}.skill-summary-card.weak .skill-summary-action{color:#dc2626}.skill-summary-card.weak .skill-summary-action:hover{background:#fecaca}.skill-groups{display:flex;flex-direction:column;gap:8px}.skill-group{border:1px solid #e2e8f0;border-radius:4px;overflow:hidden;background:#fff}.skill-group-header{width:100%;display:flex;justify-content:space-between;align-items:center;padding:14px 16px;background:#f8fafc;border:none;cursor:pointer;font-size:.95rem;font-weight:500;color:#1e293b;transition:background .2s}.skill-group-header:hover{background:#f1f5f9}.skill-group-header[aria-expanded=true] .skill-group-toggle{transform:rotate(180deg)}.skill-group-title{display:flex;align-items:center;gap:10px}.skill-dot{width:12px;height:12px;border-radius:4px}.skill-dot.weak{background:#ef4444}.skill-dot.medium{background:#f59e0b}.skill-dot.strong{background:#22c55e}.skill-group-count{font-weight:400;color:#64748b;font-size:.85rem}.skill-group-toggle{transition:transform .3s ease;color:#64748b;font-size:.8rem}.skill-group-content{padding:0;max-height:300px;overflow-y:auto}.skill-group-content .skill-item{display:flex;align-items:center;gap:12px;padding:12px 16px;border-top:1px solid #e2e8f0}.skill-group-content .skill-item:first-child{border-top:none}.skill-item-info{flex:1;min-width:0}.skill-item-name{font-weight:500;color:#1e293b;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;font-size:.9rem}.skill-item-bar{width:80px;height:6px;background:#e2e8f0;border-radius:3px;overflow:hidden}.skill-item-bar-fill{height:100%;border-radius:3px;transition:width .3s 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h3{margin:0;display:flex;align-items:center;gap:8px}@media(max-width:768px){.progress-stats-grid{grid-template-columns:repeat(2,1fr)}.skill-summary{flex-direction:column}.skill-summary-card{min-width:100%}.history-item{flex-wrap:wrap}.history-item-main{width:100%}.history-item-stats{width:100%;justify-content:space-between;margin-top:8px}.skill-item-bar{display:none}}@media(max-width:480px){.progress-stats-grid{grid-template-columns:repeat(2,1fr);gap:10px}.stat-card{padding:14px 10px}.stat-value{font-size:1.4rem}.section-header{flex-direction:column;align-items:flex-start;gap:12px}.pagination-controls{flex-wrap:wrap}}.streaming-progress{width:100%;height:4px;background:#e2e8f0;border-radius:2px;margin-top:8px;overflow:hidden}.streaming-progress-bar{height:100%;background:var(--primary);border-radius:2px;animation:streamingProgress 2s ease-in-out infinite;width:30%}@keyframes streamingProgress{0%{transform:translate(-100%)}to{transform:translate(400%)}}.generation-progress{padding:16px;background:linear-gradient(135deg,#f0f9ff,#e0f2fe);border-radius:12px;border:1px solid #bae6fd;max-width:400px;margin:0 auto}.generation-progress .progress-message{display:flex;align-items:center;gap:12px;margin-bottom:12px;font-size:1rem;color:#0369a1;font-weight:500}.generation-progress .progress-spinner{width:20px;height:20px;border:3px solid #bae6fd;border-top-color:#0284c7;border-radius:50%;animation:spin 1s linear infinite}.generation-progress .progress-text{animation:fadeInOut 4s ease-in-out infinite}@keyframes fadeInOut{0%,to{opacity:1}50%{opacity:.7}}.generation-progress .progress-bar-container{width:100%;height:8px;background:#e0f2fe;border-radius:4px;overflow:hidden;margin-bottom:8px}.generation-progress .progress-bar-fill{height:100%;width:0%;background:linear-gradient(90deg,#0284c7,#0ea5e9,#38bdf8);background-size:200% 100%;border-radius:4px;transition:width .5s ease-out;animation:shimmer 2s linear infinite}@keyframes shimmer{0%{background-position:200% 0}to{background-position:-200% 0}}.generation-progress .progress-time{font-size:.85rem;color:#64748b;text-align:right}.generation-progress .elapsed-time{font-weight:600;color:#0369a1}#tutor-chat-container{position:fixed;bottom:24px;right:24px;width:380px;max-width:calc(100vw - 48px);height:500px;max-height:calc(100vh - 100px);background:#fff;border-radius:4px;border:1px solid var(--border);z-index:1001;display:flex;flex-direction:column;overflow:hidden;transform:translateY(10px);opacity:0;visibility:hidden;transition:all .2s ease}#tutor-chat-container.open{transform:translateY(0);opacity:1;visibility:visible}.tutor-chat-header{background:#2563eb;color:#fff;padding:16px 20px;display:flex;align-items:center;gap:12px}.tutor-chat-header .tutor-avatar{font-size:32px}.tutor-chat-header .tutor-info{flex:1}.tutor-chat-header .tutor-info h3{margin:0;font-size:16px;font-weight:600}.tutor-chat-header .tutor-info p{margin:2px 0 0;font-size:12px;opacity:.9}.tutor-chat-header .close-chat{background:#fff3;border:none;color:#fff;width:32px;height:32px;border-radius:4px;cursor:pointer;font-size:18px;display:flex;align-items:center;justify-content:center;transition:background .2s ease}.tutor-chat-header .close-chat:hover{background:#ffffff4d}.tutor-chat-header .expand-chat{background:#fff3;border:none;color:#fff;width:32px;height:32px;border-radius:4px;cursor:pointer;font-size:16px;display:flex;align-items:center;justify-content:center;transition:background .2s ease}.tutor-chat-header .expand-chat:hover{background:#ffffff4d}#tutor-chat-container.expanded{width:600px;max-width:calc(100vw - 32px);height:calc(100vh - 100px);max-height:calc(100vh - 48px);bottom:16px;right:16px}#tutor-chat-container.expanded .expand-icon:before{content:"⛶";transform:rotate(45deg)}@media(max-width:768px){#tutor-chat-container.expanded{width:100vw;height:calc(100vh - 60px);max-width:100vw;max-height:calc(100vh - 60px);bottom:0;right:0;border-radius:4px 4px 0 0}}#tutor-chat-messages{flex:1;overflow-y:auto;padding:16px;display:flex;flex-direction:column;gap:12px;background:#f8fafc}.chat-message{display:flex;gap:10px;max-width:90%;animation:messageSlideIn .3s ease}@keyframes messageSlideIn{0%{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}.chat-message.student{align-self:flex-end;flex-direction:row-reverse}.chat-message.tutor{align-self:flex-start}.chat-avatar{width:36px;height:36px;border-radius:4px;background:#e2e8f0;display:flex;align-items:center;justify-content:center;font-size:18px;flex-shrink:0}.chat-message.tutor .chat-avatar{background:#2563eb}.chat-bubble{background:#fff;padding:12px 16px;border-radius:4px;border:1px solid var(--border);font-size:calc(1rem * var(--lesson-font-scale, 1));line-height:1.5;color:var(--text-primary)}.chat-message.student .chat-bubble{background:#2563eb;color:#fff;border-radius:4px}.chat-bubble code{background:#0000001a;padding:2px 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.login-card,body.high-contrast .topic-card,body.high-contrast .lesson-header,body.high-contrast .virtual-teacher,body.high-contrast .content-area,body.high-contrast .interaction-area,body.high-contrast .complete-card{background:#fff;border:3px solid #000000}body.high-contrast .btn{border:2px solid #000000}body.high-contrast .btn-primary{background:#000;color:#fff}body.high-contrast .btn-primary:hover{background:#333}body.high-contrast .btn-secondary{background:#fff;color:#000;border:2px solid #000000}body.high-contrast .btn-secondary:hover{background:#e5e5e5}body.high-contrast .progress-bar{background:#e5e5e5;border:2px solid #000000}body.high-contrast .progress-fill{background:#000}body.high-contrast a{color:#00e;text-decoration:underline}body.high-contrast a:visited{color:#551a8b}body.high-contrast .feedback.success{background:#fff;border:3px solid #006600;color:#060}body.high-contrast .feedback.error{background:#fff;border:3px solid #990000;color:#900}body.high-contrast 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.chat-message,body.reduced-motion .typing .dot{animation:none}@media(prefers-reduced-motion:reduce){*,*:before,*:after{animation-duration:.001ms!important;animation-iteration-count:1!important;transition-duration:.001ms!important}}body.tts-speaking .content-area{position:relative}body.tts-speaking .content-area:before{content:"🔊 Reading...";position:absolute;top:-30px;right:0;background:#10b981;color:#fff;padding:4px 12px;border-radius:4px;font-size:12px;font-weight:500}@media(max-width:480px){#accessibility-panel{width:calc(100vw - 16px);max-height:calc(100vh - 32px);border-radius:4px}.a11y-toolbar{flex-wrap:wrap}.a11y-btn{padding:6px 10px;font-size:13px}.shortcut-item{flex-direction:column;align-items:flex-start;gap:4px}}.waiting-for-content{display:flex;flex-direction:column;align-items:center;justify-content:center;padding:60px 20px;text-align:center;min-height:200px}.waiting-spinner{width:48px;height:48px;border:4px solid 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ease}.toast-notification.toast-visible{transform:translateY(0);opacity:1}.toast-icon{font-size:1.2rem;flex-shrink:0;width:24px;height:24px;display:flex;align-items:center;justify-content:center;border-radius:4px}.toast-message{flex:1;font-size:.95rem;line-height:1.4}.toast-close{background:none;border:none;color:#ffffffb3;font-size:1.25rem;cursor:pointer;padding:0;line-height:1;margin-left:8px}.toast-close:hover{color:#fff}.toast-success{background:#10b981}.toast-success .toast-icon{background:#fff3}.toast-error{background:#ef4444}.toast-error .toast-icon{background:#fff3}.toast-warning{background:#f59e0b}.toast-warning .toast-icon{background:#fff3}.toast-info{background:#2563eb}.toast-info .toast-icon{background:#fff3}.rate-limit-countdown{position:absolute;bottom:0;left:0;right:0;background:#f59e0b;color:#fff;padding:10px 16px;display:flex;align-items:center;justify-content:center;gap:8px;font-size:.9rem;font-weight:500;border-radius:0 0 12px 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.fallback-icon{color:#ef4444}.mermaid-error{background:#fffbeb;border-color:#fde68a}.mermaid-error .fallback-icon{color:#f59e0b}#accessibility-panel.open{pointer-events:auto}#accessibility-panel:not(.open){pointer-events:none}#a11y-backdrop{transition:opacity .3s ease}#a11y-backdrop:not(.open){pointer-events:none}@media(max-width:480px){.toast-notification{left:16px;right:16px;bottom:16px;max-width:none}.rate-limit-countdown{font-size:.85rem;padding:8px 12px}}.class-checkbox-group{display:flex;flex-direction:column;gap:8px;max-height:250px;overflow-y:auto;padding:12px;background:var(--surface-secondary, #f8fafc);border-radius:4px;border:1px solid var(--border-color, #e2e8f0)}.class-checkbox{display:flex;align-items:center;gap:10px;padding:10px 12px;background:#fff;border-radius:4px;cursor:pointer;transition:all .2s ease;border:2px solid transparent}.class-checkbox:hover{background:var(--surface-hover, #f1f5f9)}.class-checkbox:has(input:checked){background:var(--primary-light, 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0}.energy-transfer-diagram .energy-states-row{flex-wrap:wrap}.height-diagram .height-visual{flex-direction:column;align-items:center}}.multi-select-container .question-text{font-size:calc(1.2rem * var(--lesson-font-scale));margin-bottom:12px;font-weight:500}.multi-select-container .select-instruction{font-size:calc(.95rem * var(--lesson-font-scale));color:var(--text-secondary);margin-bottom:20px;font-style:italic}.multi-select-container .options-list{display:flex;flex-direction:column;gap:12px}.multi-select-btn{display:flex;align-items:flex-start;gap:16px;padding:16px 20px;border:2px solid var(--border);border-radius:4px;background:#fff;cursor:pointer;transition:var(--transition);text-align:left;font-size:calc(1.1rem * 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.parsons-line-code{padding-left:6em}.parsons-solution-empty{color:var(--text-secondary);font-style:italic;text-align:center;padding:40px 20px}.parsons-line-controls{display:flex;gap:8px;margin-left:auto;align-items:center}.parsons-move-controls{display:flex}.parsons-move-btn{padding:4px 8px;border:none;background:#3b82f6;color:#fff;border-radius:4px;cursor:pointer;font-size:14px;font-weight:700;min-width:32px;min-height:32px}.parsons-move-btn:hover{background:#2563eb}.parsons-move-btn:active{background:#1d4ed8}.parsons-reorder-controls{display:flex;flex-direction:column;gap:2px}.parsons-reorder-btn{padding:2px 6px;border:none;background:#6366f1;color:#fff;border-radius:3px;cursor:pointer;font-size:10px;min-width:24px}.parsons-reorder-btn:hover{background:#4f46e5}@media(max-width:768px){.parsons-line-handle{display:none}.parsons-move-btn{padding:8px 12px;font-size:16px}.parsons-reorder-btn,.parsons-indent-btn{padding:6px 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