/**
 * Universal Teacher - Main Stylesheet
 * ChatGPT-inspired interface with Chat + Canvas layout
 * 
 * Copyright © 2025 Glimbr Pty Ltd and Arn Todal. All Rights Reserved.
 */

/* ========================================
   CSS Variables (ChatGPT-inspired palette)
   ======================================== */
:root {
  /* ChatGPT Dark Theme Colors */
  --bg-primary: #212121;
  --bg-secondary: #2f2f2f;
  --bg-tertiary: #424242;
  --text-primary: #ececf1;
  --text-secondary: #c5c5d2;
  --text-tertiary: #8e8ea0;
  --border-light: rgba(255,255,255,0.1);
  --border-medium: rgba(255,255,255,0.15);
  
  /* Brand colors */
  --brand-primary: #19c37d;
  --brand-hover: #1aa975;
  --brand-light: rgba(25,195,125,0.1);
  
  /* Message colors */
  --ai-bg: #2f2f2f;
  --user-bg: transparent;
  
  /* Sidebar */
  --sidebar-bg: #171717;
  --sidebar-text: #ececf1;
  --sidebar-hover: #2a2a2f;
  
  /* Canvas */
  --canvas-bg: #ffffff;
  --canvas-header-bg: #f7f7f8;
  --tab-active: #ffffff;
  --tab-inactive: transparent;
  
  /* Spacing */
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 12px;
  --spacing-lg: 16px;
  --spacing-xl: 24px;
  --spacing-2xl: 32px;
  
  /* Border radius */
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  
  /* Font sizes (ChatGPT-like) */
  --font-xs: 12px;
  --font-sm: 14px;
  --font-md: 16px;
  --font-lg: 18px;
  --font-xl: 20px;
  --font-2xl: 24px;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 2px 8px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.12);
}

/* ========================================
   Dark Mode Variables
   ======================================== */
[data-theme="dark"] {
  --bg-primary: #212121;
  --bg-secondary: #2f2f2f;
  --bg-tertiary: #3f3f3f;
  --text-primary: #ececf1;
  --text-secondary: #b4b4b4;
  --text-tertiary: #8e8ea0;
  --border-light: #4e4e4e;
  --border-medium: #5a5a5a;
  
  --ai-bg: #2f2f2f;
  --canvas-bg: #2f2f2f;
  --canvas-header-bg: #212121;
}

/* ========================================
   Reset & Base Styles
   ======================================== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html, body {
  height: 100%;
  overflow: hidden;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', sans-serif;
  font-size: var(--font-md);
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--bg-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
  outline: none;
}

/* ========================================
   Layout
   ======================================== */
.app-container {
  display: flex;
  height: 100vh;
  width: 100vw;
  overflow: hidden;
}

/* ========================================
   Sidebar
   ======================================== */
.sidebar {
  width: 260px;
  background: var(--sidebar-bg);
  color: var(--sidebar-text);
  display: flex;
  flex-direction: column;
  border-right: 1px solid rgba(255, 255, 255, 0.1);
  transition: margin-left 0.3s ease;
  margin-left: 0;
}

.sidebar.collapsed {
  margin-left: -260px;
}

.sidebar-header {
  padding: var(--spacing-sm) var(--spacing-md);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.new-chat-btn {
  width: 100%;
  padding: var(--spacing-md);
  background: transparent;
  color: var(--sidebar-text);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: var(--radius-md);
  font-size: var(--font-sm);
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  transition: all 0.2s ease;
}

.new-chat-btn:hover {
  background: var(--sidebar-hover);
}

.sidebar-content {
  flex: 1;
  overflow-y: auto;
  padding: var(--spacing-sm);
}

.chat-history {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
}

.chat-history-item {
  padding: var(--spacing-md);
  border-radius: var(--radius-md);
  color: var(--sidebar-text);
  font-size: var(--font-sm);
  transition: background 0.2s ease;
  cursor: pointer;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.chat-history-item:hover {
  background: var(--sidebar-hover);
}

.chat-history-item.active {
  background: var(--sidebar-hover);
}

.sidebar-footer {
  padding: var(--spacing-md);
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.user-menu-btn {
  width: 100%;
  padding: var(--spacing-md);
  background: transparent;
  color: var(--sidebar-text);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  font-size: var(--font-sm);
  transition: background 0.2s ease;
}

.user-menu-btn:hover {
  background: var(--sidebar-hover);
}

.user-avatar {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.1);
  display: flex;
  align-items: center;
  justify-content: center;
}

/* ========================================
   Main Content
   ======================================== */
.main-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.top-header {
  height: 60px;
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  padding: 0 var(--spacing-lg);
  gap: var(--spacing-lg);
  background: var(--bg-primary);
}

.sidebar-toggle {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s ease;
}

.sidebar-toggle:hover {
  background: var(--bg-secondary);
}

.header-title h1 {
  font-size: var(--font-lg);
  font-weight: 600;
  color: var(--text-primary);
}

.header-actions {
  margin-left: auto;
  display: flex;
  gap: var(--spacing-sm);
}

.icon-btn {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s ease;
}

.icon-btn:hover {
  background: var(--bg-secondary);
  color: var(--text-primary);
}

/* ========================================
   Content Wrapper (Chat + Canvas)
   ======================================== */
.content-wrapper {
  flex: 1;
  display: flex;
  overflow: hidden;
}

/* ========================================
   Chat Panel
   ======================================== */
.chat-panel {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  max-width: 100%;
  transition: max-width 0.3s ease;
}

.chat-panel.with-canvas {
  max-width: 50%;
}

.messages-container {
  flex: 1;
  overflow-y: auto;
  padding: var(--spacing-xl) var(--spacing-lg);
  scroll-behavior: smooth;
}

/* Welcome Screen */
.welcome-screen {
  max-width: 900px;
  margin: 0 auto;
  padding: 10vh 0;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.welcome-icon {
  margin-bottom: var(--spacing-xl);
  color: #8e8ea0;
}

.welcome-icon svg {
  opacity: 0.6;
}

.welcome-screen h2 {
  font-size: var(--font-2xl);
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
  color: var(--text-primary);
}

.welcome-subtitle {
  font-size: var(--font-lg);
  color: var(--text-secondary);
  margin-bottom: var(--spacing-2xl);
}

/* Category View */
.category-view {
  margin-top: var(--spacing-2xl);
}

.category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--spacing-lg);
  max-width: 800px;
  margin: 0 auto;
}

.category-card {
  padding: var(--spacing-2xl) var(--spacing-lg);
  background: #2f2f2f;
  border: 2px solid rgba(255,255,255,0.1);
  border-radius: var(--radius-lg);
  transition: all 0.2s ease;
  cursor: pointer;
  text-align: center;
}

.category-card:hover {
  background: #3d3d3d;
  border-color: var(--brand-primary);
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(0,0,0,0.3);
}

.category-icon {
  font-size: 48px;
  margin-bottom: var(--spacing-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--brand-primary);
}

.category-icon svg,
.course-icon svg {
  color: var(--brand-primary);
  stroke: currentColor;
}

.category-card h3 {
  font-size: var(--font-lg);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--spacing-xs);
}

.category-card p {
  font-size: var(--font-sm);
  color: var(--text-secondary);
  line-height: 1.4;
}

/* Course List View */
.course-list-view {
  margin-top: var(--spacing-xl);
  text-align: left;
  max-width: 900px;
  margin: 0 auto;
  padding: var(--spacing-xl);
}

.course-list-header {
  margin-bottom: var(--spacing-xl);
}

.back-to-categories {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-md);
  background: transparent;
  border: 1px solid rgba(255,255,255,0.2);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: var(--font-sm);
  font-weight: 500;
  transition: all 0.2s ease;
  cursor: pointer;
  margin-bottom: var(--spacing-lg);
}

.back-to-categories:hover {
  background: var(--bg-secondary);
  border-color: var(--brand-primary);
}

.course-list-header h3 {
  font-size: var(--font-xl);
  font-weight: 600;
  color: var(--text-primary);
}

.course-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: var(--spacing-lg);
}

.course-card {
  padding: var(--spacing-lg);
  background: #2f2f2f;
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: var(--radius-lg);
  transition: all 0.2s ease;
  cursor: pointer;
  text-align: left;
}

.course-card:hover {
  background: #3d3d3d;
  border-color: var(--brand-primary);
  transform: translateY(-2px);
  box-shadow: 0 4px 16px rgba(0,0,0,0.2);
}

.course-icon {
  font-size: 32px;
  margin-bottom: var(--spacing-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--brand-primary);
}

.course-card h4 {
  font-size: var(--font-md);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--spacing-xs);
}

.course-card p {
  font-size: var(--font-sm);
  color: var(--text-secondary);
  line-height: 1.4;
}

.quick-prompts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: var(--spacing-md);
  margin-top: var(--spacing-2xl);
}

.prompt-card {
  padding: var(--spacing-lg);
  background: #2f2f2f;
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: var(--radius-lg);
  transition: all 0.15s ease;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
  text-align: left;
  cursor: pointer;
}

.prompt-card:hover {
  background: #3d3d3d;
  border-color: rgba(255,255,255,0.2);
}

.prompt-icon {
  color: #8e8ea0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.prompt-text {
  font-size: var(--font-sm);
  font-weight: 500;
  color: var(--text-primary);
}

/* ========================================
   Messages
   ======================================== */
.message-group {
  max-width: 720px;
  margin: 0 auto var(--spacing-xl);
  display: flex;
  gap: var(--spacing-lg);
}

.message-avatar {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-size: 20px;
}

.message-avatar.ai {
  background: var(--brand-primary);
  color: white;
}

.message-avatar.user {
  background: var(--bg-tertiary);
  color: var(--text-primary);
}

.message-content {
  flex: 1;
  min-width: 0;
}

.message-role {
  font-size: var(--font-sm);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--spacing-xs);
}

.message-text {
  font-size: var(--font-md);
  line-height: 1.7;
  color: var(--text-primary);
  white-space: pre-wrap;
  word-wrap: break-word;
}

.message-text p {
  margin: 0 0 var(--spacing-md);
}

.message-text p:last-child {
  margin-bottom: 0;
}

/* Code blocks in messages - Terminal style */
.message-text code {
  background: rgba(0, 0, 0, 0.05);
  padding: 2px 6px;
  border-radius: 4px;
  font-family: 'Fira Code', 'SF Mono', 'Courier New', monospace;
  font-size: 14px;
  color: #d73a49;
  border: 1px solid rgba(0, 0, 0, 0.1);
}

.message-text pre {
  background: #1e1e1e;
  padding: 0;
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin: var(--spacing-md) 0;
  border: 1px solid #333;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
}

.message-text pre code {
  display: block;
  background: none;
  padding: var(--spacing-lg);
  color: #d4d4d4;
  font-family: 'Fira Code', 'SF Mono', 'Courier New', monospace;
  font-size: 14px;
  line-height: 1.6;
  overflow-x: auto;
  border: none;
}

/* Code block header (language tag) */
.code-block-wrapper {
  background: #1e1e1e;
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin: var(--spacing-md) 0;
  border: 1px solid #333;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
}

.code-block-header {
  background: #2d2d2d;
  padding: 8px 16px;
  border-bottom: 1px solid #333;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.code-block-language {
  font-family: 'Inter', sans-serif;
  font-size: 12px;
  color: #858585;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.code-block-copy {
  background: transparent;
  border: none;
  color: #858585;
  font-size: 12px;
  cursor: pointer;
  padding: 4px 8px;
  border-radius: 4px;
  transition: all 0.2s ease;
  font-family: 'Inter', sans-serif;
}

.code-block-copy:hover {
  background: rgba(255, 255, 255, 0.1);
  color: #d4d4d4;
}

.code-block-content {
  background: #1e1e1e;
  padding: var(--spacing-lg);
  overflow-x: auto;
}

.code-block-content code {
  display: block;
  color: #d4d4d4;
  font-family: 'Fira Code', 'SF Mono', 'Courier New', monospace;
  font-size: 14px;
  line-height: 1.6;
  background: none;
  padding: 0;
  border: none;
}

/* Syntax highlighting colors (basic) */
.code-block-content .keyword {
  color: #c678dd;
}

.code-block-content .string {
  color: #98c379;
}

.code-block-content .comment {
  color: #5c6370;
  font-style: italic;
}

.code-block-content .function {
  color: #61afef;
}

/* Canvas preview in message */
.canvas-preview {
  margin-top: var(--spacing-md);
  padding: var(--spacing-md);
  background: var(--bg-secondary);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: all 0.2s ease;
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.canvas-preview:hover {
  background: var(--bg-tertiary);
  border-color: var(--brand-primary);
  box-shadow: var(--shadow-md);
}

.canvas-preview-icon {
  font-size: 32px;
}

.canvas-preview-content {
  flex: 1;
}

.canvas-preview-title {
  font-size: var(--font-sm);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--spacing-xs);
}

.canvas-preview-subtitle {
  font-size: var(--font-xs);
  color: var(--text-secondary);
}

/* Quick reply buttons */
.quick-replies {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
  margin-top: var(--spacing-md);
}

.quick-reply-btn {
  padding: var(--spacing-sm) var(--spacing-md);
  background: var(--bg-secondary);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  font-size: var(--font-sm);
  color: var(--text-primary);
  transition: all 0.2s ease;
}

.quick-reply-btn:hover {
  background: var(--bg-tertiary);
  border-color: var(--brand-primary);
}

/* ========================================
   Input Area
   ======================================== */
.input-area {
  padding: var(--spacing-md) var(--spacing-lg) var(--spacing-xl);
  background: var(--bg-primary);
  border-top: none;
  position: relative;
}

.input-container {
  max-width: 800px;
  margin: 0 auto;
  position: relative;
  background: var(--bg-secondary);
  border: 1px solid var(--border-medium);
  border-radius: 24px;
  padding: 10px 14px;
  display: flex;
  align-items: flex-end;
  gap: var(--spacing-md);
  transition: all 0.2s ease;
  box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

.input-container:focus-within {
  border-color: var(--brand-primary);
  background: var(--bg-secondary);
}

.message-input {
  flex: 1;
  border: none !important;
  background: transparent;
  font-size: 16px;
  line-height: 1.5;
  color: var(--text-primary);
  resize: none;
  max-height: 200px;
  min-height: 24px;
  padding: 8px 4px;
  overflow-y: auto;
  outline: none !important;
  box-shadow: none !important;
}

.message-input:focus {
  border: none !important;
  outline: none !important;
  box-shadow: none !important;
}

.message-input::placeholder {
  color: var(--text-tertiary);
}

.send-button {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  background: var(--brand-primary);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s ease;
  flex-shrink: 0;
}

.send-button:hover:not(:disabled) {
  background: var(--brand-hover);
}

.send-button:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

.input-footer {
  max-width: 720px;
  margin: var(--spacing-sm) auto 0;
  text-align: center;
}

.input-hint {
  font-size: var(--font-xs);
  color: var(--text-tertiary);
}

/* ========================================
   Canvas Panel
   ======================================== */
.canvas-panel {
  width: 0;
  background: var(--canvas-bg);
  border-left: 1px solid var(--border-light);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  transition: width 0.3s ease;
}

.canvas-panel.visible {
  width: 50%;
}

.canvas-header {
  height: 48px;
  background: var(--canvas-header-bg);
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  padding: 0 var(--spacing-md);
  gap: var(--spacing-md);
}

.canvas-tabs {
  flex: 1;
  display: flex;
  gap: var(--spacing-xs);
  overflow-x: auto;
  scrollbar-width: none;
}

.canvas-tabs::-webkit-scrollbar {
  display: none;
}

.canvas-tab {
  padding: var(--spacing-sm) var(--spacing-md);
  background: var(--tab-inactive);
  border: 1px solid transparent;
  border-radius: var(--radius-md) var(--radius-md) 0 0;
  font-size: var(--font-sm);
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  white-space: nowrap;
  transition: all 0.2s ease;
  position: relative;
}

.canvas-tab:hover {
  background: rgba(0, 0, 0, 0.05);
}

.canvas-tab.active {
  background: var(--tab-active);
  color: var(--text-primary);
  font-weight: 500;
  border-color: var(--border-light);
  border-bottom-color: var(--canvas-bg);
}

.canvas-tab-icon {
  font-size: 16px;
}

.canvas-tab-close {
  width: 20px;
  height: 20px;
  margin-left: var(--spacing-xs);
  border-radius: 4px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-tertiary);
  transition: all 0.2s ease;
}

.canvas-tab-close:hover {
  background: rgba(0, 0, 0, 0.1);
  color: var(--text-primary);
}

.canvas-actions {
  display: flex;
  gap: var(--spacing-xs);
}

.canvas-content {
  flex: 1;
  overflow: auto;
  position: relative;
  background: var(--canvas-bg);
}

.canvas-empty-state {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
  color: var(--text-tertiary);
}

.canvas-empty-state svg {
  margin-bottom: var(--spacing-md);
  opacity: 0.5;
}

.canvas-empty-state p {
  font-size: var(--font-md);
  font-weight: 500;
  margin-bottom: var(--spacing-xs);
  color: var(--text-secondary);
}

.canvas-empty-state span {
  font-size: var(--font-sm);
}

.canvas-controls {
  height: 48px;
  background: var(--canvas-header-bg);
  border-top: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--spacing-md);
}

.controls-left,
.controls-center,
.controls-right {
  display: flex;
  gap: var(--spacing-xs);
  align-items: center;
}

.control-btn {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s ease;
}

.control-btn:hover:not(:disabled) {
  background: var(--bg-tertiary);
  color: var(--text-primary);
}

.control-btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

.zoom-level {
  font-size: var(--font-sm);
  color: var(--text-secondary);
  min-width: 50px;
  text-align: center;
}

/* ========================================
   Canvas Content Types
   ======================================== */
.canvas-code-editor {
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
}

.canvas-code-toolbar {
  height: 52px;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  padding: 0 var(--spacing-md);
  gap: var(--spacing-sm);
}

.language-select {
  padding: 6px 12px;
  background: white;
  border: 1px solid var(--border-light);
  border-radius: 6px;
  font-size: 14px;
  font-family: 'Inter', sans-serif;
  font-weight: 500;
  color: var(--text-primary);
  cursor: pointer;
  outline: none;
}

.language-select:hover {
  border-color: var(--brand-primary);
}

.language-select:focus {
  border-color: var(--brand-primary);
  box-shadow: 0 0 0 1px var(--brand-primary);
}

.run-code-btn {
  padding: 8px 20px;
  background: var(--brand-primary);
  color: white;
  border: none;
  border-radius: 6px;
  font-size: 14px;
  font-family: 'Inter', sans-serif;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  margin-left: 8px;
}

.run-code-btn:hover {
  background: var(--brand-hover);
  transform: translateY(-1px);
  box-shadow: 0 2px 8px rgba(16, 163, 127, 0.3);
}

.run-code-btn:active {
  transform: translateY(0);
}

.copy-code-btn {
  padding: 8px 20px;
  background: white;
  color: var(--text-primary);
  border: 1px solid var(--border-light);
  border-radius: 6px;
  font-size: 14px;
  font-family: 'Inter', sans-serif;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
}

.copy-code-btn:hover {
  background: var(--bg-tertiary);
  border-color: var(--border-medium);
}

.code-editor-area {
  flex: 1;
  background: #1e1e1e;
  color: #d4d4d4;
  font-family: 'Fira Code', 'Courier New', monospace;
  font-size: 14px;
  line-height: 1.6;
  padding: var(--spacing-lg);
  overflow: auto;
  white-space: pre-wrap;
  word-wrap: break-word;
  outline: none;
}

.code-editor-area:focus {
  outline: 2px solid var(--brand-primary);
  outline-offset: -2px;
}

.code-console {
  height: 200px;
  background: #1e1e1e;
  border-top: 1px solid #333;
  color: #d4d4d4;
  font-family: 'Fira Code', monospace;
  font-size: 13px;
  padding: var(--spacing-md);
  overflow: auto;
}

/* ========================================
   Loading States
   ======================================== */
.loading-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
}

.loading-spinner {
  width: 48px;
  height: 48px;
  border: 4px solid rgba(255, 255, 255, 0.2);
  border-top-color: white;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.typing-indicator {
  display: flex;
  gap: 6px;
  padding: var(--spacing-md) 0;
}

.typing-dot {
  width: 8px;
  height: 8px;
  background: var(--text-tertiary);
  border-radius: 50%;
  animation: typing 1.4s infinite;
}

.typing-dot:nth-child(2) {
  animation-delay: 0.2s;
}

.typing-dot:nth-child(3) {
  animation-delay: 0.4s;
}

@keyframes typing {
  0%, 60%, 100% { opacity: 0.3; transform: translateY(0); }
  30% { opacity: 1; transform: translateY(-8px); }
}

/* ========================================
   Responsive (Mobile)
   ======================================== */
@media (max-width: 768px) {
  .sidebar {
    position: fixed;
    left: 0;
    top: 0;
    bottom: 0;
    z-index: 100;
    transform: translateX(-100%);
  }
  
  .sidebar.visible {
    transform: translateX(0);
  }
  
  .chat-panel {
    max-width: 100%;
  }
  
  .canvas-panel {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    width: 100%;
    z-index: 50;
    transform: translateX(100%);
  }
  
  .canvas-panel.visible {
    transform: translateX(0);
  }
  
  .messages-container {
    padding: var(--spacing-lg) var(--spacing-md);
  }
  
  .input-area {
    padding: var(--spacing-md);
  }
  
  .welcome-screen {
    padding: var(--spacing-lg) 0;
  }
  
  .quick-prompts {
    grid-template-columns: 1fr;
  }
  
  .category-grid {
    grid-template-columns: 1fr;
    gap: var(--spacing-md);
  }
  
  .course-grid {
    grid-template-columns: 1fr;
    gap: var(--spacing-md);
  }
  
  .course-list-view {
    padding: var(--spacing-md);
  }
}

/* ========================================
   Accessibility
   ======================================== */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

/* Focus styles */
button:focus-visible,
textarea:focus-visible {
  outline: 2px solid var(--brand-primary);
  outline-offset: 2px;
}

/* ========================================
   Video Modal
   ======================================== */
.video-modal {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 10000;
  display: flex;
  align-items: center;
  justify-content: center;
}

.video-modal-backdrop {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.85);
  backdrop-filter: blur(4px);
}

.video-modal-content {
  position: relative;
  width: 90%;
  max-width: 960px;
  aspect-ratio: 16/9;
  background: #000;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: 0 24px 48px rgba(0, 0, 0, 0.5);
  display: flex;
  flex-direction: column;
}

.video-modal-header {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  padding: var(--spacing-md) var(--spacing-lg);
  background: linear-gradient(to bottom, rgba(0,0,0,0.8) 0%, transparent 100%);
  display: flex;
  justify-content: space-between;
  align-items: center;
  z-index: 2;
  opacity: 0;
  transition: opacity 0.3s ease;
}

.video-modal-content:hover .video-modal-header {
  opacity: 1;
}

.video-modal-header h3 {
  font-size: var(--font-md);
  color: white;
  margin: 0;
  text-shadow: 0 1px 2px rgba(0,0,0,0.5);
}

.video-modal-close {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.2);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  transition: all 0.2s ease;
}

.video-modal-close:hover {
  background: rgba(255, 255, 255, 0.4);
  transform: scale(1.1);
}

.video-modal-body {
  flex: 1;
  width: 100%;
  height: 100%;
}

.video-modal-body iframe {
  width: 100%;
  height: 100%;
  border: none;
}

/* ========================================
   Lesson Tabs
   ======================================== */
.lesson-tabs {
  display: flex;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-xl);
  border-bottom: 1px solid var(--border-light);
  padding-bottom: 0;
}

.lesson-tab {
  padding: var(--spacing-md) var(--spacing-xl);
  font-size: var(--font-sm);
  font-weight: 500;
  color: var(--text-tertiary);
  cursor: pointer;
  transition: all 0.2s ease;
  border-bottom: 2px solid transparent;
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.lesson-tab:hover {
  color: var(--text-primary);
  background: var(--bg-secondary);
}

.lesson-tab.active {
  color: var(--brand-primary);
  border-bottom-color: var(--brand-primary);
}

/* ========================================
   Teacher Resources
   ======================================== */
.teacher-resources {
  background: var(--bg-secondary);
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
}

.teacher-section {
  margin-bottom: var(--spacing-2xl);
}

.teacher-section h3 {
  font-size: var(--font-lg);
  color: var(--brand-primary);
  margin-bottom: var(--spacing-md);
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.teacher-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-lg);
}

.teacher-card {
  background: var(--bg-tertiary);
  padding: var(--spacing-lg);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-light);
}

.teacher-card h4 {
  font-size: var(--font-md);
  margin-bottom: var(--spacing-sm);
  color: var(--text-primary);
}

.teacher-list {
  margin: 0;
  padding-left: var(--spacing-xl);
  color: var(--text-secondary);
}

.teacher-list li {
  margin-bottom: var(--spacing-sm);
}

.script-item {
  margin-bottom: var(--spacing-lg);
  padding-left: var(--spacing-md);
  border-left: 2px solid var(--border-medium);
}

.script-stage {
  font-weight: 600;
  color: var(--text-primary);
  font-size: var(--font-sm);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: var(--spacing-xs);
}

.script-content {
  color: var(--text-secondary);
  font-size: var(--font-md);
}

.pitfall-item {
  margin-bottom: var(--spacing-md);
}

.pitfall-issue {
  font-weight: 600;
  color: #ef4444;
  margin-bottom: var(--spacing-xs);
}

.pitfall-solution {
  color: var(--text-secondary);
}

.resource-actions {
  display: flex;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-xl);
}

/* ========================================
   Print Styles (for Lesson Plan PDF)
   ======================================== */
@media print {
  body {
    background: white !important;
    color: black !important;
    overflow: visible !important;
  }

  .sidebar, 
  .top-header, 
  .lesson-tabs, 
  .lesson-nav, 
  .resource-actions,
  .secondary-btn,
  .back-to-chat {
    display: none !important;
  }

  .main-content {
    margin: 0 !important;
    padding: 0 !important;
    overflow: visible !important;
  }

  #lessonContainer {
    display: block !important;
    padding: 0 !important;
    margin: 0 !important;
  }

  .lesson-container {
    max-width: 100% !important;
    margin: 0 !important;
  }

  .teacher-resources {
    background: white !important;
    padding: 0 !important;
    color: black !important;
  }

  .teacher-card, .teacher-section {
    page-break-inside: avoid;
    border-color: #eee !important;
    background: white !important;
    color: black !important;
  }

  .teacher-section h3 {
    color: #333 !important;
    border-bottom: 2px solid #333;
    padding-bottom: 5px;
  }

  .teacher-card h4 {
    color: #333 !important;
  }

  .teacher-list, .script-content, .pitfall-solution {
    color: #444 !important;
  }

  .lesson-title {
    color: black !important;
    font-size: 28pt !important;
    margin-top: 0 !important;
  }

  .lesson-meta {
    color: #666 !important;
    margin-bottom: 30px !important;
  }

  /* Watermark or footer for print */
  body::after {
    content: "Generated by Universal Teacher • Professional Lesson Plan";
    position: fixed;
    bottom: 20px;
    right: 20px;
    font-size: 10pt;
    color: #999;
  }
}

/* ========================================
   Scrollbar Styling (ChatGPT-like)
   ======================================== */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: var(--border-medium);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-tertiary);
}

/* ========================================
   Utilities
   ======================================== */
.hidden {
  display: none !important;
}

.fade-in {
  animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

.slide-in-right {
  animation: slideInRight 0.3s ease;
}

@keyframes slideInRight {
  from { transform: translateX(100%); }
  to { transform: translateX(0); }
}