/* ==========================================================================
   THE COPYWRITER'S APPRENTICESHIP - EDITORIAL DESIGN SYSTEM
   Inspired by classic typography, book publishing, and editorial manuscripts.
   ========================================================================== */

:root {
  /* Warm Parchment Light Theme */
  --bg-primary: #f7f5ef;
  --bg-surface: #ffffff;
  --bg-surface-alt: #f0ece1;
  --bg-surface-tint: #eae5d8;
  --text-primary: #181b19;
  --text-secondary: #4a524d;
  --text-muted: #758079;
  
  --border-subtle: #e2ddd3;
  --border-strong: #232724;
  
  /* Brand Editorial Accents */
  --crimson: #c93b2b;
  --crimson-subtle: #fbeee8;
  --crimson-border: #f2c0b7;
  
  --teal: #1d6f72;
  --teal-subtle: #e8f4f4;
  --teal-border: #a8d5d6;
  
  --amber: #b26a00;
  --amber-subtle: #fef5e7;
  --amber-border: #f8d7a4;
  
  --dark-slab: #141614;
  --dark-slab-text: #f7f5ef;

  --font-serif: 'Newsreader', 'Playfair Display', Georgia, Cambria, serif;
  --font-sans: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Space Mono', Menlo, Consolas, monospace;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.08);
  --shadow-xl: 0 20px 40px rgba(0, 0, 0, 0.12);

  --sidebar-width: 320px;
  --header-height: 64px;
}

/* Dark Editorial Mode */
[data-theme="dark"] {
  --bg-primary: #121413;
  --bg-surface: #181c19;
  --bg-surface-alt: #1f2521;
  --bg-surface-tint: #262e29;
  --text-primary: #f2eee6;
  --text-secondary: #b5c0b9;
  --text-muted: #7c8880;
  
  --border-subtle: #29322c;
  --border-strong: #d5cfc4;

  --crimson: #e05345;
  --crimson-subtle: #291816;
  --crimson-border: #5c2822;

  --teal: #38a3a5;
  --teal-subtle: #132729;
  --teal-border: #1d5557;

  --amber: #e7a834;
  --amber-subtle: #2b200e;
  --amber-border: #60451a;

  --dark-slab: #0a0c0a;
  --dark-slab-text: #f7f5ef;

  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 4px 14px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.6);
}

/* Base Resets */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font-sans);
  line-height: 1.65;
  min-height: 100vh;
  overflow-x: hidden;
  transition: background-color 0.25s ease, color 0.25s ease;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-serif);
  font-weight: 700;
  line-height: 1.25;
  color: var(--text-primary);
  letter-spacing: -0.015em;
}

p {
  margin-bottom: 1.25rem;
}

p:last-child {
  margin-bottom: 0;
}

a {
  color: inherit;
  text-decoration: none;
}

code, pre, .font-mono {
  font-family: var(--font-mono);
}

/* Layout Architecture */
.app-container {
  display: flex;
  min-height: 100vh;
  flex-direction: column;
}

/* Top App Header */
.top-header {
  position: sticky;
  top: 0;
  z-index: 50;
  height: var(--header-height);
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 1.5rem;
  backdrop-filter: blur(8px);
}

.header-left, .header-right {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.brand-title {
  display: flex;
  flex-direction: column;
}

.brand-kicker {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--crimson);
  font-weight: 700;
}

.brand-heading {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: var(--text-primary);
}

.btn-icon {
  background: transparent;
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  width: 38px;
  height: 38px;
  border-radius: 8px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-icon:hover {
  background: var(--bg-surface-alt);
  color: var(--text-primary);
  border-color: var(--text-muted);
}

.btn-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.45rem 0.9rem;
  font-size: 0.8125rem;
  font-weight: 600;
  border-radius: 9999px;
  border: 1px solid var(--border-subtle);
  background: var(--bg-surface);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-pill:hover, .btn-pill.active {
  background: var(--text-primary);
  color: var(--bg-surface);
  border-color: var(--text-primary);
}

.btn-pill.accent {
  background: var(--crimson);
  color: #ffffff;
  border-color: var(--crimson);
}
.btn-pill.accent:hover {
  opacity: 0.9;
}

/* Global Progress Bar */
.reading-progress-track {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: var(--bg-surface-alt);
}

.reading-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--crimson), #e76f51, var(--teal));
  width: 0%;
  transition: width 0.15s ease-out;
}

/* Main Workspace Split */
.main-wrapper {
  display: flex;
  flex: 1;
  width: 100%;
  position: relative;
}

/* Navigation Sidebar */
.course-sidebar {
  width: var(--sidebar-width);
  background: var(--bg-surface);
  border-right: 1px solid var(--border-subtle);
  display: flex;
  flex-direction: column;
  position: sticky;
  top: var(--header-height);
  height: calc(100vh - var(--header-height));
  overflow-y: auto;
  z-index: 30;
  transition: transform 0.3s ease;
}

.sidebar-header {
  padding: 1.25rem;
  border-bottom: 1px solid var(--border-subtle);
}

.sidebar-stats-card {
  background: var(--bg-surface-alt);
  border-radius: 8px;
  padding: 0.85rem 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 0.75rem;
}

.stat-item {
  display: flex;
  flex-direction: column;
}

.stat-val {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text-primary);
}

.stat-lbl {
  font-size: 0.6875rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.sidebar-search-box {
  padding: 0.75rem 1.25rem;
  border-bottom: 1px solid var(--border-subtle);
  position: relative;
}

.sidebar-search-input {
  width: 100%;
  padding: 0.5rem 0.75rem 0.5rem 2rem;
  font-size: 0.8125rem;
  border: 1px solid var(--border-subtle);
  border-radius: 6px;
  background: var(--bg-primary);
  color: var(--text-primary);
  outline: none;
}

.sidebar-search-input:focus {
  border-color: var(--text-muted);
}

.sidebar-search-icon {
  position: absolute;
  left: 1.75rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  pointer-events: none;
}

/* Module & Level Accordion */
.modules-accordion {
  flex: 1;
  padding: 0.5rem 0;
}

.module-item {
  border-bottom: 1px solid var(--border-subtle);
}

.module-trigger {
  width: 100%;
  text-align: left;
  background: transparent;
  border: none;
  padding: 1rem 1.25rem;
  cursor: pointer;
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.75rem;
  transition: background 0.15s ease;
}

.module-trigger:hover {
  background: var(--bg-surface-alt);
}

.module-trigger.active {
  background: var(--bg-surface-tint);
}

.module-meta-left {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

.module-num {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--crimson);
}

.module-title-text {
  font-family: var(--font-serif);
  font-size: 0.95rem;
  font-weight: 700;
  line-height: 1.3;
  color: var(--text-primary);
}

.module-levels-tag {
  font-size: 0.7rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

.module-chevron {
  transition: transform 0.2s ease;
  color: var(--text-muted);
  margin-top: 0.25rem;
}

.module-item.open .module-chevron {
  transform: rotate(180deg);
}

.module-levels-list {
  display: none;
  background: var(--bg-primary);
  border-top: 1px solid var(--border-subtle);
  padding: 0.5rem 0;
}

.module-item.open .module-levels-list {
  display: block;
}

.level-nav-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.55rem 1.25rem 0.55rem 2rem;
  font-size: 0.8125rem;
  color: var(--text-secondary);
  transition: all 0.15s ease;
}

.level-nav-link:hover {
  color: var(--text-primary);
  background: var(--bg-surface-alt);
}

.level-nav-link.active {
  color: var(--crimson);
  font-weight: 700;
  background: var(--bg-surface);
  border-left: 3px solid var(--crimson);
}

.level-nav-badge {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  padding: 0.1rem 0.4rem;
  border-radius: 4px;
  background: var(--bg-surface-alt);
  color: var(--text-muted);
}

.level-nav-link.completed .level-nav-badge {
  background: #06d6a020;
  color: #06d6a0;
}

/* Content Area */
.content-viewport {
  flex: 1;
  max-width: 960px;
  margin: 0 auto;
  padding: 2.5rem 2.5rem 6rem;
  min-width: 0;
}

/* Book Cover / Hero Section */
.book-cover-banner {
  background: var(--dark-slab);
  color: var(--dark-slab-text);
  border-radius: 12px;
  padding: 4rem 3rem;
  margin-bottom: 3.5rem;
  position: relative;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  border-bottom: 4px solid var(--crimson);
}

.cover-kicker {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--crimson);
  margin-bottom: 1.5rem;
  font-weight: 700;
}

.cover-title {
  font-family: var(--font-serif);
  font-size: 3rem;
  font-weight: 900;
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin-bottom: 1.25rem;
  color: #ffffff;
}

.cover-subtitle {
  font-family: var(--font-serif);
  font-size: 1.35rem;
  font-style: italic;
  color: #d1d8d3;
  margin-bottom: 2rem;
  max-width: 650px;
  line-height: 1.45;
}

.cover-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-top: 1px solid rgba(255, 255, 255, 0.15);
  padding-top: 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: #9aa8a0;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

.cover-author {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 800;
  color: #ffffff;
}

/* Module Cover Card (Editorial Style) */
.module-cover-card {
  background: var(--dark-slab);
  color: var(--dark-slab-text);
  border-radius: 10px;
  padding: 3rem 2.5rem;
  margin-bottom: 3rem;
  position: relative;
  box-shadow: var(--shadow-md);
  border-bottom: 3px solid var(--crimson);
}

.module-cover-pre {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--crimson);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  font-weight: 700;
  margin-bottom: 1rem;
}

.module-cover-h1 {
  font-size: 2.25rem;
  font-weight: 800;
  color: #ffffff;
  margin-bottom: 0.5rem;
}

.module-cover-sub {
  font-family: var(--font-serif);
  font-style: italic;
  font-size: 1.15rem;
  color: #b5c3ba;
  margin-bottom: 1.75rem;
}

.module-cover-footer {
  border-top: 1px solid rgba(255, 255, 255, 0.12);
  padding-top: 1rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: #8c9991;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  display: flex;
  justify-content: space-between;
}

/* Level Section */
.level-container {
  margin-bottom: 4.5rem;
  animation: fadeIn 0.3s ease-in;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.level-header {
  border-bottom: 2px solid var(--border-strong);
  padding-bottom: 1.5rem;
  margin-bottom: 2.5rem;
}

.level-kicker {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 800;
  color: var(--crimson);
  text-transform: uppercase;
  letter-spacing: 0.15em;
  margin-bottom: 0.5rem;
}

.level-number-huge {
  font-family: var(--font-mono);
  font-size: 3.5rem;
  font-weight: 900;
  line-height: 1;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
  letter-spacing: -0.05em;
}

.level-title {
  font-size: 2.25rem;
  font-weight: 800;
  margin-bottom: 0.75rem;
}

.level-subtitle {
  font-family: var(--font-serif);
  font-size: 1.2rem;
  font-style: italic;
  color: var(--text-secondary);
}

/* Lesson Container */
.lesson-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: 8px;
  padding: 2.25rem;
  margin-bottom: 3rem;
  box-shadow: var(--shadow-sm);
}

.lesson-code-tag {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--crimson);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 0.35rem;
}

.lesson-title {
  font-size: 1.75rem;
  margin-bottom: 1.25rem;
}

.lesson-lead {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-style: italic;
  line-height: 1.6;
  color: var(--text-primary);
  border-left: 3px solid var(--border-strong);
  padding-left: 1.25rem;
  margin: 1.5rem 0;
}

.lesson-body {
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.75;
  margin-bottom: 1.75rem;
}

.lesson-body p {
  margin-bottom: 1.2rem;
}

/* ==========================================================================
   AUTHENTIC BOOK MARKUPS (Styled exact to PDF)
   ========================================================================== */

/* 1. KEY IDEA */
.markup-key-idea {
  background: var(--bg-surface-alt);
  border-left: 4px solid var(--text-primary);
  padding: 1.25rem 1.5rem;
  margin: 1.75rem 0;
  border-radius: 0 6px 6px 0;
}

.markup-key-idea .markup-tag {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 800;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--text-primary);
  margin-bottom: 0.4rem;
  display: block;
}

.markup-key-idea .markup-content {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.5;
}

/* 2. MANUSCRIPT (Strike-through & Editor Notes) */
.markup-manuscript {
  background: #fdfcf9;
  border: 1px solid #d9d2c5;
  border-radius: 6px;
  padding: 1.5rem;
  margin: 1.75rem 0;
  position: relative;
}

[data-theme="dark"] .markup-manuscript {
  background: #191c1a;
  border-color: #364039;
}

.manuscript-title {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--text-muted);
  font-weight: 700;
  margin-bottom: 0.85rem;
  border-bottom: 1px dashed var(--border-subtle);
  padding-bottom: 0.5rem;
}

.manuscript-original {
  font-family: var(--font-serif);
  font-size: 1.05rem;
  color: #7b857f;
  text-decoration: line-through;
  text-decoration-color: var(--crimson);
  text-decoration-thickness: 1.5px;
  margin-bottom: 0.75rem;
  line-height: 1.5;
}

.manuscript-editor {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--crimson);
  font-weight: 600;
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.manuscript-editor::before {
  content: "✎";
  font-size: 1rem;
}

.manuscript-revised {
  background: #eaf4ed;
  border-left: 3px solid #2d6a4f;
  padding: 0.85rem 1rem;
  font-family: var(--font-serif);
  font-size: 1.05rem;
  color: #1b4332;
  border-radius: 0 4px 4px 0;
  margin-bottom: 0.75rem;
  line-height: 1.5;
}

[data-theme="dark"] .manuscript-revised {
  background: #14281e;
  border-color: #52b788;
  color: #d8f3dc;
}

.manuscript-commentary {
  font-size: 0.85rem;
  color: var(--text-secondary);
  font-style: italic;
  margin-top: 0.5rem;
}

/* 3. THINK */
.markup-think {
  background: var(--amber-subtle);
  border: 1px solid var(--amber-border);
  border-radius: 6px;
  padding: 1.25rem 1.5rem;
  margin: 1.75rem 0;
}

.markup-think .markup-tag {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 800;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--amber);
  margin-bottom: 0.4rem;
  display: block;
}

.markup-think .markup-content {
  font-size: 0.95rem;
  color: var(--text-primary);
  line-height: 1.55;
}

/* 4. WRITE EXERCISE (Interactive Workbook) */
.markup-write {
  background: var(--bg-surface);
  border: 1.5px solid var(--border-strong);
  border-radius: 8px;
  padding: 1.5rem;
  margin: 2rem 0;
  box-shadow: var(--shadow-sm);
}

.markup-write-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.85rem;
}

.markup-write .markup-tag {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 800;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  background: var(--text-primary);
  color: var(--bg-surface);
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
}

.exercise-prompt {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 1.25rem;
  line-height: 1.5;
}

.exercise-textarea {
  width: 100%;
  min-height: 110px;
  padding: 0.85rem 1rem;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  background: var(--bg-primary);
  color: var(--text-primary);
  border: 1px solid var(--border-subtle);
  border-radius: 6px;
  resize: vertical;
  line-height: 1.5;
  transition: border-color 0.2s;
  outline: none;
}

.exercise-textarea:focus {
  border-color: var(--text-primary);
  background: var(--bg-surface);
}

.exercise-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 0.75rem;
  font-size: 0.75rem;
  color: var(--text-muted);
}

.exercise-actions {
  display: flex;
  gap: 0.5rem;
}

.btn-mini {
  padding: 0.35rem 0.75rem;
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: 4px;
  border: 1px solid var(--border-subtle);
  background: var(--bg-surface-alt);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s ease;
}

.btn-mini:hover {
  background: var(--text-primary);
  color: var(--bg-surface);
  border-color: var(--text-primary);
}

.btn-mini.save-active {
  background: #2a9d8f;
  color: #fff;
  border-color: #2a9d8f;
}

/* 5. COMMON MISTAKE */
.markup-mistake {
  background: var(--crimson-subtle);
  border: 1px solid var(--crimson-border);
  border-radius: 6px;
  padding: 1.25rem 1.5rem;
  margin: 1.75rem 0;
}

.markup-mistake .markup-tag {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 800;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--crimson);
  margin-bottom: 0.4rem;
  display: block;
}

.markup-mistake .markup-content {
  font-size: 0.95rem;
  color: var(--text-primary);
  line-height: 1.55;
}

/* 6. REMEMBER (Solid Black Slab) */
.markup-remember {
  background: var(--dark-slab);
  color: var(--dark-slab-text);
  border-radius: 6px;
  padding: 1.35rem 1.6rem;
  margin: 2rem 0;
  box-shadow: var(--shadow-sm);
}

.markup-remember .markup-tag {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 800;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: #8c9991;
  margin-bottom: 0.4rem;
  display: block;
}

.markup-remember .markup-content {
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.5;
  color: #f7f5ef;
}

/* 7. NOTICE / BECOMES */
.markup-notice-becomes {
  border: 1.5px solid var(--teal);
  border-radius: 8px;
  overflow: hidden;
  margin: 1.75rem 0;
}

.notice-box {
  background: var(--teal-subtle);
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--teal-border);
}

.notice-source {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 700;
  color: var(--teal);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 0.5rem;
}

.notice-quote {
  font-family: var(--font-serif);
  font-style: italic;
  font-size: 1rem;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
}

.notice-takeaway {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.becomes-box {
  background: var(--bg-surface);
  padding: 1.25rem 1.5rem;
}

.becomes-tag {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 800;
  color: var(--teal);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 0.4rem;
}

.becomes-copy {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.4;
  margin-bottom: 0.4rem;
}

.becomes-note {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Tables & Grid Systems */
.editorial-table-wrap {
  overflow-x: auto;
  margin: 1.75rem 0;
  border: 1px solid var(--border-subtle);
  border-radius: 6px;
}

.editorial-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
  text-align: left;
}

.editorial-table th {
  background: var(--bg-surface-alt);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 0.85rem 1.25rem;
  border-bottom: 1px solid var(--border-subtle);
  color: var(--text-primary);
}

.editorial-table td {
  padding: 0.85rem 1.25rem;
  border-bottom: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  line-height: 1.5;
}

.editorial-table tr:last-child td {
  border-bottom: none;
}

.editorial-table tr:hover td {
  background: var(--bg-surface-alt);
}

/* Checkpoints & Capstones */
.checkpoint-card, .capstone-card {
  border: 2px solid var(--teal);
  border-radius: 8px;
  overflow: hidden;
  margin: 3rem 0;
  background: var(--bg-surface);
  box-shadow: var(--shadow-md);
}

.checkpoint-header, .capstone-header {
  background: var(--teal);
  color: #ffffff;
  padding: 1.25rem 1.75rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.checkpoint-kicker {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  font-weight: 800;
}

.checkpoint-title-text {
  font-family: var(--font-serif);
  font-size: 1.35rem;
  font-weight: 700;
  margin-top: 0.2rem;
}

.checkpoint-body {
  padding: 1.75rem;
}

.checkpoint-brief {
  font-size: 0.95rem;
  color: var(--text-primary);
  line-height: 1.6;
  margin-bottom: 1.5rem;
  white-space: pre-line;
}

.strong-answer-drawer {
  background: var(--teal-subtle);
  border-left: 3px solid var(--teal);
  padding: 1.25rem;
  border-radius: 0 6px 6px 0;
  margin-top: 1.5rem;
  display: none;
  animation: fadeIn 0.2s ease-out;
}

.strong-answer-drawer.open {
  display: block;
}

.strong-answer-header {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 800;
  color: var(--teal);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 0.5rem;
}

.strong-answer-text {
  font-size: 0.9rem;
  color: var(--text-primary);
  line-height: 1.55;
}

/* So-What Ladder Component */
.so-what-ladder {
  background: var(--bg-surface-alt);
  border-radius: 8px;
  padding: 1.5rem;
  margin: 1.75rem 0;
}

.ladder-step {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  margin-bottom: 1rem;
  position: relative;
}

.ladder-step::before {
  content: "";
  position: absolute;
  left: 17px;
  top: 32px;
  bottom: -15px;
  width: 2px;
  background: var(--border-subtle);
}

.ladder-step:last-child {
  margin-bottom: 0;
}

.ladder-step:last-child::before {
  display: none;
}

.ladder-badge {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 700;
  background: var(--text-primary);
  color: var(--bg-surface);
  min-width: 36px;
  height: 36px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  z-index: 2;
}

.ladder-step.final .ladder-badge {
  background: var(--teal);
}

.ladder-content {
  flex: 1;
  padding-top: 0.35rem;
}

.ladder-label {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  text-transform: uppercase;
  color: var(--text-muted);
  font-weight: 700;
}

.ladder-text {
  font-size: 0.95rem;
  color: var(--text-primary);
  font-weight: 600;
}

/* Interactive Modals */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.65);
  backdrop-filter: blur(4px);
  z-index: 100;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
}

.modal-overlay.open {
  display: flex;
}

.modal-window {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: 12px;
  width: 100%;
  max-width: 760px;
  max-height: 85vh;
  overflow-y: auto;
  box-shadow: var(--shadow-xl);
  display: flex;
  flex-direction: column;
}

.modal-header {
  padding: 1.25rem 1.75rem;
  border-bottom: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.modal-title {
  font-family: var(--font-serif);
  font-size: 1.35rem;
}

.modal-body {
  padding: 1.75rem;
  flex: 1;
}

/* Practice Lab Tools View */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
  margin-top: 1.5rem;
}

.tool-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: 8px;
  padding: 1.5rem;
  cursor: pointer;
  transition: all 0.2s ease;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.tool-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--text-primary);
}

.tool-badge {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 700;
  color: var(--crimson);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 0.5rem;
}

.tool-title {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.tool-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.5;
  margin-bottom: 1rem;
}

/* Bottom Pager */
.bottom-pager {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-top: 1px solid var(--border-subtle);
  padding-top: 2rem;
  margin-top: 4rem;
}

.pager-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.25rem;
  border-radius: 6px;
  border: 1px solid var(--border-subtle);
  background: var(--bg-surface);
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s ease;
}

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

/* Mobile Responsive */
@media (max-width: 900px) {
  .course-sidebar {
    position: fixed;
    left: 0;
    top: var(--header-height);
    transform: translateX(-100%);
    box-shadow: var(--shadow-xl);
  }

  .course-sidebar.mobile-open {
    transform: translateX(0);
  }

  .content-viewport {
    padding: 1.5rem 1.25rem 4rem;
  }

  .cover-title {
    font-size: 2.2rem;
  }

  .cover-subtitle {
    font-size: 1.1rem;
  }

  .book-cover-banner {
    padding: 2.5rem 1.5rem;
  }
}

/* Print Styles */
@media print {
  .top-header, .course-sidebar, .bottom-pager, .btn-icon, .btn-mini, .exercise-footer {
    display: none !important;
  }
  
  .content-viewport {
    max-width: 100% !important;
    padding: 0 !important;
  }
  
  body {
    background: #ffffff !important;
    color: #000000 !important;
  }
}