/* Newsprint Theme — Newspaper Style for Standalone Viewer */
@import url('https://fonts.googleapis.com/css2?family=UnifrakturMaguntia&family=Newsreader:ital,opsz,wght@0,6..72,200..800;1,6..72,200..800&family=Merriweather:ital,wght@0,300;0,400;0,700;1,400&family=Source+Sans+3:ital,wght@0,400;0,600;0,700;1,400&display=swap');

:root {
  --color-paper: #f9f7f1;
  --color-paper-dark: #eae6da;
  --color-ink: #2f2f2f;
  --color-ink-light: #5a5a5a;
  --color-ink-faint: #8a8a8a;
  --color-rule: #2f2f2f;
  --color-rule-light: #c4c0b6;
  --color-accent: #8b0000;
  --color-link: #2f2f2f;
  --color-link-hover: #8b0000;
  --color-white: #ffffff;

  --font-masthead: 'UnifrakturMaguntia', 'Newsreader', Georgia, serif;
  --font-headline: 'Newsreader', Georgia, serif;
  --font-body: 'Merriweather', Georgia, serif;
  --font-sans: 'Source Sans 3', system-ui, -apple-system, sans-serif;

  /* Legacy variable mappings for seamless compatibility */
  --ink: var(--color-ink);
  --muted: var(--color-ink-light);
  --blue: var(--color-accent);
  --teal: #1f5f5b;
  --orange: #9c4115;
  --paper: var(--color-paper);
  --line: var(--color-rule-light);
  --pale: var(--color-paper-dark);
  --blue-light: #f1ebd9;
  --radius: 0px;
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--color-paper);
  color: var(--color-ink);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
}

button, input, select {
  font: inherit;
}

.skip {
  position: absolute;
  top: -100px;
  left: 1rem;
  background: var(--color-ink);
  color: var(--color-paper);
  padding: 8px 16px;
  z-index: 1000;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 600;
  text-decoration: none;
  border-radius: 0 0 4px 4px;
  transition: top 0.15s ease;
}

.skip:focus {
  top: 0;
}

button, a, input, select, summary {
  -webkit-tap-highlight-color: transparent;
}

a {
  color: var(--color-link);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  transition: color 0.15s ease;
}

a:hover {
  color: var(--color-link-hover);
}

button {
  cursor: pointer;
}

button:disabled {
  cursor: default;
  opacity: 0.45;
}

button:focus-visible, a:focus-visible, input:focus-visible, select:focus-visible, summary:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
}

/* Typography Standards */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-headline);
  color: var(--color-ink);
  line-height: 1.2;
}

h1 {
  font-size: clamp(2.2rem, 4vw, 3.4rem);
  font-weight: 700;
  letter-spacing: -0.025em;
  margin-bottom: 0.8rem;
  border-bottom: 1px solid var(--color-rule);
  padding-bottom: 0.6rem;
}

h2 {
  font-size: 1.65rem;
  font-weight: 700;
  letter-spacing: -0.015em;
  margin: 1.5rem 0 0.6rem;
}

h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin: 1.2rem 0 0.5rem;
}

p, li {
  font-family: var(--font-body);
  font-size: 1.02rem;
  line-height: 1.8;
  color: var(--color-ink);
}

p {
  margin-bottom: 1.1rem;
}

strong {
  font-weight: 700;
  color: var(--color-ink);
}

/* ==========================================================================
   Masthead Header (Newspaper Broadside)
   ========================================================================== */

header.masthead {
  background: var(--color-paper);
  max-width: 1240px;
  margin: 0 auto;
  padding: 1rem 1.5rem 0;
  width: 100%;
  text-align: center;
  border-bottom: 1px solid var(--color-rule);
}

.masthead__meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--color-rule);
  font-family: var(--font-sans);
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--color-ink-light);
}

.masthead__title-wrap {
  text-align: center;
  margin: 0.6rem 0 0.4rem;
}

.masthead__title {
  display: flex;
  justify-content: center;
  align-items: center;
  margin: 0.1rem 0;
}

.masthead__logo-text {
  font-family: var(--font-masthead);
  font-size: clamp(2.8rem, 6vw, 4.4rem);
  font-weight: 700;
  letter-spacing: -0.01em;
  line-height: 1;
  color: var(--color-ink);
  margin: 0;
  border-bottom: none;
  padding-bottom: 0;
}

.masthead__subtitle {
  font-family: var(--font-body);
  font-style: italic;
  font-size: 0.95rem;
  color: var(--color-ink-light);
  margin: 0.35rem 0 0.7rem;
}

nav.masthead__nav {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 0;
  border-top: 3px double var(--color-rule);
  border-bottom: 1px solid var(--color-rule);
  margin-top: 0.4rem;
  padding: 0;
  background: var(--color-paper);
  position: relative;
}

nav.masthead__nav a {
  color: var(--color-ink);
  text-decoration: none;
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  padding: 0.6rem 1.4rem;
  border-right: 1px solid var(--color-rule-light);
  transition: all 0.15s ease;
  white-space: nowrap;
}

nav.masthead__nav a:first-child {
  border-left: 1px solid var(--color-rule-light);
}

nav.masthead__nav a:hover {
  color: var(--color-accent);
  background: var(--color-paper-dark);
}

nav.masthead__nav a.active {
  background: var(--color-ink);
  color: var(--color-paper);
}

.masthead__menu-btn {
  display: none;
  margin-left: auto;
  background: var(--color-paper-dark);
  border: 1px solid var(--color-rule);
  color: var(--color-ink);
  font-family: var(--font-sans);
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  padding: 6px 12px;
}

/* ==========================================================================
   Broadsheet App Layout (Sidebar + Main Article)
   ========================================================================== */

.app-layout {
  display: grid;
  grid-template-columns: 290px minmax(0, 1fr);
  max-width: 1240px;
  margin: 0 auto;
  width: 100%;
  background: var(--color-paper);
  border-left: 1px solid var(--color-rule-light);
  border-right: 1px solid var(--color-rule-light);
  flex: 1;
}

/* Sidebar: The Broadsheet Index */
.sidebar {
  padding: 1.8rem 1.2rem 2.5rem 1.5rem;
  border-right: 1px solid var(--color-rule);
  background: var(--color-paper);
  height: 100vh;
  position: sticky;
  top: 0;
  overflow-y: auto;
  scrollbar-width: thin;
  scrollbar-color: var(--color-rule-light) var(--color-paper);
}

.rail-heading {
  font-family: var(--font-sans);
  font-size: 0.76rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-accent);
  border-bottom: 2px solid var(--color-rule);
  padding-bottom: 4px;
  margin-bottom: 6px;
}

.rail-note {
  font-family: var(--font-body);
  font-style: italic;
  font-size: 0.84rem;
  color: var(--color-ink-light);
  margin-bottom: 1.4rem;
}

.nav-group {
  margin-bottom: 1.5rem;
}

.nav-group h2 {
  font-family: var(--font-sans);
  font-size: 0.74rem;
  font-weight: 700;
  color: var(--color-ink);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  border-bottom: 1px solid var(--color-rule-light);
  padding-bottom: 4px;
  margin: 0 0 8px;
}

.nav-group a {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 6px 8px;
  text-decoration: none;
  color: var(--color-ink);
  font-family: var(--font-sans);
  font-size: 0.86rem;
  line-height: 1.35;
  border-left: 2px solid transparent;
  transition: all 0.12s ease;
  border-radius: 0;
}

.nav-group a:hover {
  background: var(--color-paper-dark);
  color: var(--color-accent);
  border-left-color: var(--color-rule-light);
}

.nav-group a.active {
  background: var(--color-ink);
  color: var(--color-paper);
  font-weight: 600;
  border-left-color: var(--color-accent);
}

.nav-group a.active .lesson-num {
  color: #e5a9a9;
}

.lesson-num {
  font-family: var(--font-headline);
  font-weight: 700;
  font-size: 0.82rem;
  color: var(--color-accent);
  min-width: 18px;
}

.rail-footer {
  border-top: 1px solid var(--color-rule-light);
  padding-top: 1.2rem;
  font-family: var(--font-sans);
  font-size: 0.75rem;
  color: var(--color-ink-light);
  line-height: 1.6;
}

/* ==========================================================================
   Main Article & Lesson View
   ========================================================================== */

main {
  padding: 2.2rem clamp(1.5rem, 3.5vw, 3.2rem) 3.5rem;
  min-width: 0;
  background: var(--color-paper);
}

.lesson-head {
  max-width: 860px;
}

.crumb {
  display: flex;
  justify-content: space-between;
  gap: 15px;
  margin-bottom: 1.2rem;
  font-family: var(--font-sans);
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-ink-light);
  border-bottom: 1px solid var(--color-rule-light);
  padding-bottom: 6px;
}

.eyebrow {
  font-family: var(--font-sans);
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--color-accent);
  margin-bottom: 6px;
}

.lead {
  font-family: var(--font-headline);
  font-style: italic;
  font-size: 1.28rem;
  line-height: 1.55;
  color: var(--color-ink-light);
  max-width: 780px;
  margin-bottom: 1.8rem;
}

.opening {
  display: flex;
  flex-direction: column;
  gap: 2rem;
  max-width: 860px;
}

.opening.single {
  display: flex;
}

.explanation p:first-of-type::first-letter {
  font-family: var(--font-headline);
  font-size: 2.2rem;
  font-weight: 700;
  color: var(--color-accent);
  line-height: 1;
  padding-right: 2px;
}

/* Analogy Callout */
.analogy {
  border-left: 3px solid var(--color-rule);
  background: var(--color-paper-dark);
  padding: 14px 18px;
  margin: 1rem 0 1.8rem;
}

.analogy h3 {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--color-accent);
  margin: 0 0 6px;
}

.analogy p {
  font-family: var(--font-body);
  font-size: 0.98rem;
  font-style: italic;
  line-height: 1.65;
  margin: 0;
  color: var(--color-ink);
}

/* ==========================================================================
   Broadsheet Dispatches: Presentation Gold, Quizzes, Formulas
   ========================================================================== */

/* Formula Box & Equation Cards */
.formula-card {
  background: #faf8f3;
  border: 1px solid var(--color-rule);
  border-top: 4px solid var(--color-accent);
  padding: 22px 24px;
  margin: 24px 0;
  box-shadow: 4px 4px 0px rgba(47, 47, 47, 0.08);
}

.formula-card__header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 14px;
  flex-wrap: wrap;
}

.formula-tag {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  background: var(--color-accent);
  color: #ffffff;
  padding: 4px 10px;
}

.formula-title {
  font-family: var(--font-sans);
  font-size: 0.88rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-ink);
}

.formula-card__equation {
  font-family: ui-monospace, SFMono-Regular, Consolas, "Courier New", monospace;
  font-size: 1.08rem;
  font-weight: 600;
  line-height: 1.8;
  color: var(--color-ink);
  background: #ffffff;
  border: 1px solid var(--color-rule-light);
  padding: 16px 20px;
  margin-bottom: 18px;
  overflow-x: auto;
  letter-spacing: 0.02em;
}

.formula-card__breakdown {
  margin-top: 14px;
}

.breakdown-title {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-ink-light);
  margin-bottom: 12px;
  border-bottom: 1px dashed var(--color-rule-light);
  padding-bottom: 6px;
}

.terms-grid {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.term-row {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  padding: 10px 14px;
  background: #ffffff;
  border: 1px solid var(--color-rule-light);
  border-left: 4px solid var(--color-accent);
}

.term-symbol {
  font-family: ui-monospace, SFMono-Regular, Consolas, monospace;
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--color-accent);
  min-width: 58px;
  padding-top: 2px;
}

.term-details {
  display: flex;
  flex-direction: column;
  gap: 3px;
  flex: 1;
}

.term-name {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--color-ink);
}

.term-meaning {
  font-family: var(--font-body);
  font-size: 0.92rem;
  line-height: 1.55;
  color: var(--color-ink-light);
}

.formula {
  background: var(--color-paper-dark);
  color: var(--color-ink);
  border: 3px double var(--color-rule);
  padding: 18px 22px;
  font-family: ui-monospace, SFMono-Regular, Consolas, "Courier New", monospace;
  font-size: 0.98rem;
  line-height: 1.8;
  overflow-x: auto;
  margin: 22px 0;
}

.formula small {
  display: block;
  font-family: var(--font-sans);
  font-size: 0.78rem;
  color: var(--color-ink-light);
  margin-top: 6px;
}

/* Patient Case Calculations */
.patient-calc {
  background: #f4f0e6;
  border: 1px solid var(--color-rule);
  border-top: 3px solid var(--color-accent);
  padding: 22px;
  margin: 24px 0;
}

.patient-calc h4 {
  font-family: var(--font-sans);
  font-size: 0.84rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--color-accent);
  margin: 0 0 12px;
  border-bottom: 1px solid var(--color-rule-light);
  padding-bottom: 4px;
}

.patient-calc ul, .patient-calc ol {
  padding-left: 1.4rem;
}

.patient-calc li {
  margin-bottom: 8px;
}

/* Presentation Gold: Rounds Memorandum */
.presentation-gold {
  background: #fbf8ee;
  border: 3px double var(--color-accent);
  padding: 20px 24px;
  margin: 26px 0;
  position: relative;
}

.presentation-gold h4 {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--color-accent);
  margin: 0 0 8px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.presentation-gold p {
  font-family: var(--font-headline);
  font-style: italic;
  font-size: 1.14rem;
  line-height: 1.6;
  color: var(--color-ink);
  margin: 0;
}

/* Interactive Quiz Box */
.quiz-box {
  background: var(--color-paper);
  border: 2px solid var(--color-rule);
  padding: 24px;
  margin: 28px 0;
  box-shadow: 4px 4px 0px rgba(47,47,47,0.12);
}

.quiz-box h4 {
  font-family: var(--font-sans);
  font-size: 0.82rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--color-accent);
  border-bottom: 1px solid var(--color-rule-light);
  padding-bottom: 6px;
  margin: 0 0 12px;
}

.quiz-box p {
  font-family: var(--font-body);
  font-size: 1.02rem;
  margin-bottom: 14px;
}

.quiz-options {
  display: grid;
  gap: 8px;
}

.quiz-opt {
  background: var(--color-paper-dark);
  border: 1px solid var(--color-rule);
  color: var(--color-ink);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  padding: 10px 14px;
  text-align: left;
  transition: all 0.15s ease;
  border-radius: 0;
}

.quiz-opt:hover {
  background: var(--color-ink);
  color: var(--color-paper);
}

.quiz-opt.correct {
  background: #255331;
  color: #ffffff;
  border-color: #255331;
  font-weight: 600;
}

.quiz-opt.incorrect {
  background: var(--color-accent);
  color: #ffffff;
  border-color: var(--color-accent);
}

.quiz-explanation {
  background: var(--color-paper-dark);
  border: 1px solid var(--color-rule-light);
  padding: 14px;
  font-family: var(--font-body);
  font-size: 0.92rem;
  line-height: 1.65;
  margin-top: 14px;
  display: none;
}

.quiz-explanation.show {
  display: block;
}

/* Assumption Cards Grid */
.assumption-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin: 20px 0;
}

.assumption-card {
  background: var(--color-paper);
  border: 1px solid var(--color-rule);
  padding: 16px;
}

.assumption-card h5 {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-ink);
  margin-bottom: 6px;
}

.assumption-card p {
  font-family: var(--font-sans);
  font-size: 0.86rem;
  line-height: 1.5;
  color: var(--color-ink-light);
  margin: 0;
}

.assumption-card .good {
  color: #1f5f5b;
  font-weight: 700;
}

.assumption-card .bad {
  color: var(--color-accent);
  font-weight: 700;
}

/* Statistical Metrics Grid */
.metric-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin: 20px 0;
}

.metric {
  background: var(--color-paper-dark);
  border: 1px solid var(--color-rule);
  padding: 14px 16px;
}

.metric span {
  font-family: var(--font-sans);
  font-size: 0.74rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-ink-light);
  display: block;
  margin-bottom: 4px;
}

.metric b {
  font-family: var(--font-headline);
  font-size: 1.7rem;
  font-weight: 700;
  color: var(--color-ink);
  display: block;
  line-height: 1.2;
}

/* ==========================================================================
   Laboratory Apparatus / Experimental Bench (.lab)
   ========================================================================== */

.lab {
  background: var(--color-paper);
  border: 2px solid var(--color-rule);
  box-shadow: 4px 4px 0px rgba(47,47,47,0.1);
  overflow: hidden;
  margin: 24px 0;
}

.lab-top {
  background: var(--color-paper-dark);
  border-bottom: 2px solid var(--color-rule);
  padding: 12px 18px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
}

.demo-label {
  font-family: var(--font-body);
  font-style: italic;
  font-size: 0.78rem;
  color: var(--color-ink-light);
  text-transform: none;
  letter-spacing: normal;
}

.lab-body {
  padding: 22px;
  background: var(--color-paper);
}

/* SVG Charts */
.chart {
  width: 100%;
  display: block;
  height: auto;
  max-height: 360px;
}

.chart text {
  font-family: var(--font-sans);
  fill: var(--color-ink);
  font-size: 12px;
}

.chart .grid {
  stroke: var(--color-rule-light);
  stroke-width: 1;
}

.chart .axis {
  stroke: var(--color-rule);
  stroke-width: 1.5;
}

.chart .curve {
  fill: none;
  stroke: var(--color-ink);
  stroke-width: 2.5;
}

.chart .secondary {
  fill: none;
  stroke: var(--color-accent);
  stroke-width: 2;
  stroke-dasharray: 4 3;
}

.chart .point {
  fill: var(--color-accent);
  stroke: var(--color-paper);
  stroke-width: 1.5;
}

/* Controls */
.controls {
  display: grid;
  gap: 14px;
  margin-top: 18px;
  border-top: 1px solid var(--color-rule-light);
  padding-top: 16px;
}

.range-label {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-sans);
  font-size: 0.84rem;
  font-weight: 600;
  color: var(--color-ink);
  margin-bottom: 6px;
}

.range-label output {
  font-family: var(--font-sans);
  font-weight: 700;
  color: var(--color-accent);
}

input[type=range] {
  width: 100%;
  accent-color: var(--color-accent);
  cursor: ew-resize;
  height: 20px;
}

input[type=number], select {
  max-width: 100%;
  width: 100%;
  padding: 8px 12px;
  border: 1px solid var(--color-rule);
  background: var(--color-paper);
  color: var(--color-ink);
  border-radius: 0;
  font-family: var(--font-sans);
}

.control-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

/* Buttons */
.button, button.outline, .mode-switch button {
  display: inline-flex;
  justify-content: center;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  border-radius: 0;
  border: 1px solid var(--color-rule);
  font-family: var(--font-sans);
  font-size: 0.82rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  text-decoration: none;
  background: var(--color-ink);
  color: var(--color-paper);
  min-height: 38px;
  transition: all 0.15s ease;
}

.button:hover, .mode-switch button[aria-pressed=true] {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-white);
}

button.outline {
  background: var(--color-paper);
  color: var(--color-ink);
  border-color: var(--color-rule);
}

button.outline:hover {
  background: var(--color-paper-dark);
  color: var(--color-accent);
  border-color: var(--color-accent);
}

.small {
  font-size: 0.75rem;
  padding: 5px 10px;
  min-height: 30px;
}

.lab-actions {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-top: 14px;
}

.readout {
  padding: 12px 16px;
  margin-top: 16px;
  background: var(--color-paper-dark);
  border: 1px solid var(--color-rule);
  font-family: var(--font-body);
  font-size: 0.92rem;
  line-height: 1.6;
}

.readout strong {
  color: var(--color-accent);
}

/* Metric Cards & Grids */
.metric-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 12px;
  margin: 16px 0;
}

.metric-card {
  padding: 14px 16px;
  background: var(--color-paper);
  border: 1px solid var(--color-rule);
  border-radius: 4px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.metric-card .metric-val {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-ink);
}

.metric-card .metric-label {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-ink-light);
}

/* Data Tables */
.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--color-rule);
  margin: 12px 0;
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--font-sans);
  font-size: 0.84rem;
}

.data-table th, .data-table td {
  padding: 8px 12px;
  border-bottom: 1px solid var(--color-rule-light);
  text-align: left;
}

.data-table th {
  background: var(--color-paper-dark);
  border-bottom: 2px solid var(--color-rule);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-ink);
}

.data-table .missing {
  color: var(--color-accent);
  font-weight: 700;
  background: #fbf0e8;
}

/* Code Blocks */
pre {
  background: #252422;
  color: #f4f0e6;
  font-size: 0.84rem;
  line-height: 1.7;
  padding: 18px 20px;
  border-left: 4px solid var(--color-accent);
  overflow-x: auto;
  margin: 16px 0;
  border-radius: 0;
}

code {
  font-family: ui-monospace, SFMono-Regular, Consolas, "Courier New", monospace;
}

.code-caption {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  color: var(--color-ink-light);
  margin-top: 6px;
}

/* Formula Breakdown Cards */
.formula-card {
  margin: 1.5rem 0;
  padding: 1.5rem;
  background: var(--color-paper-dark);
  border: 1px solid var(--color-rule);
  border-left: 4px solid var(--color-accent);
  border-radius: 4px;
}

.formula-card__equation {
  font-size: 1.22rem;
  color: var(--color-ink);
  margin-bottom: 1rem;
  text-align: center;
  padding: 0.9rem 1.25rem;
  background: var(--color-paper);
  border: 1px dashed var(--color-rule);
  border-radius: 4px;
  overflow-x: auto;
  letter-spacing: 0.02em;
}

.formula-card__equation .katex-display {
  margin: 0.25rem 0;
}

.formula-card__equation .katex {
  font-size: 1.15em;
}

.formula-card__caption {
  font-family: var(--font-sans);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-ink-light);
  margin-bottom: 0.75rem;
  font-weight: 700;
}

.terms-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 0.85rem;
  margin-top: 0.85rem;
}

.term-item {
  padding: 0.85rem 1rem;
  background: var(--color-paper);
  border: 1px solid var(--color-rule);
  border-radius: 4px;
  font-size: 0.88rem;
  line-height: 1.5;
}

.term-item code {
  font-weight: 700;
  color: var(--color-accent);
  font-size: 0.95rem;
  background: #fbf0e8;
  padding: 2px 6px;
  border-radius: 3px;
  display: inline-block;
  margin-bottom: 4px;
}

.term-item code .katex {
  font-size: 1.05em;
  font-weight: 600;
}

/* Standalone .formula Blocks */
.formula {
  margin: 1.25rem 0;
  padding: 1rem 1.25rem;
  background: var(--color-paper);
  border: 1px solid var(--color-rule);
  border-left: 3px solid var(--color-accent);
  border-radius: 4px;
  text-align: center;
  overflow-x: auto;
}

.formula .katex-display {
  margin: 0.25rem 0;
}

.formula small {
  display: block;
  margin-top: 0.6rem;
  font-family: var(--font-sans);
  font-size: 0.8rem;
  color: var(--color-ink-light);
  text-align: left;
}

/* Lesson Bottom Navigation */
.lesson-bottom {
  display: flex;
  align-items: stretch;
  justify-content: space-between;
  gap: 20px;
  border-top: 3px double var(--color-rule);
  margin-top: 3.5rem;
  padding-top: 2rem;
  padding-bottom: 1.5rem;
}

.nav-btn__spacer {
  flex: 1;
}

.nav-btn {
  display: flex;
  flex-direction: column;
  flex: 1;
  max-width: 420px;
  padding: 16px 22px;
  border: 1px solid var(--color-rule);
  background: #ffffff;
  text-decoration: none;
  border-radius: 4px;
  transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.04);
  position: relative;
  overflow: hidden;
}

.nav-btn:hover {
  border-color: var(--color-accent);
  box-shadow: 0 6px 20px rgba(187, 77, 39, 0.12);
  transform: translateY(-2px);
}

.nav-btn__dir {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--color-accent);
  margin-bottom: 4px;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: transform 0.2s ease;
}

.nav-btn__title {
  font-family: var(--font-display, serif);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--color-ink);
  line-height: 1.35;
}

.prev-btn {
  text-align: left;
  align-items: flex-start;
}

.prev-btn:hover .nav-btn__dir {
  transform: translateX(-4px);
}

.next-btn {
  text-align: right;
  align-items: flex-end;
  margin-left: auto;
  background: #fdfbf7;
  border-color: #d8cfc4;
}

.next-btn:hover .nav-btn__dir {
  transform: translateX(4px);
}

.next-btn.complete-btn {
  background: #252422;
  border-color: #252422;
}

.next-btn.complete-btn .nav-btn__dir {
  color: #e29578;
}

.next-btn.complete-btn .nav-btn__title {
  color: #fdfbf7;
}

.next-btn.complete-btn:hover {
  background: var(--color-accent);
  border-color: var(--color-accent);
}

.next-btn.complete-btn:hover .nav-btn__dir,
.next-btn.complete-btn:hover .nav-btn__title {
  color: #ffffff;
}

@media (max-width: 680px) {
  .lesson-bottom {
    flex-direction: column;
  }
  .nav-btn {
    max-width: 100%;
  }
}

/* Site Footer */
footer.site-footer {
  text-align: center;
  padding: 1.4rem 1.5rem 1.6rem;
  background: var(--color-paper);
  border-top: 3px double var(--color-rule);
  max-width: 1240px;
  margin: 0 auto;
  width: 100%;
}

}

.footer-credit {
  font-family: var(--font-body);
  font-style: italic;
  font-size: 0.8rem;
  color: var(--color-ink-light);
  opacity: 0.75;
  letter-spacing: 0.05em;
}

/* ==========================================================================
   Pedagogical Discovery Components (17-Step Core Architecture)
   ========================================================================== */

/* 1. Predict Before Reveal */
.predict-reveal {
  background: var(--color-paper);
  border: 2px dashed var(--color-rule);
  border-radius: 6px;
  padding: 20px;
  margin: 24px 0;
  transition: border-color 0.2s ease;
}

.predict-reveal.revealed {
  border-style: solid;
  border-color: var(--color-accent);
}

.predict-header {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
}

.predict-badge {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  background: var(--color-accent);
  color: #fff;
  padding: 3px 8px;
  border-radius: 3px;
}

.predict-prompt {
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--color-ink);
  margin-bottom: 14px;
  line-height: 1.4;
}

.predict-options {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 16px;
}

.predict-opt {
  font-family: var(--font-sans);
  font-size: 0.92rem;
  text-align: left;
  padding: 12px 16px;
  background: var(--color-paper-dark);
  border: 1px solid var(--color-rule);
  border-radius: 4px;
  cursor: pointer;
  color: var(--color-ink);
  transition: all 0.15s ease;
}

.predict-opt:hover:not(:disabled) {
  background: #f0eae1;
  border-color: var(--color-ink-light);
  transform: translateX(4px);
}

.predict-opt.selected {
  font-weight: 700;
  border-color: var(--color-accent);
  background: #fbeee6;
}

.predict-reveal-content {
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px solid var(--color-rule-light);
  animation: fadeIn 0.3s ease-in-out;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

/* 2. Token-by-Token Code Explainer */
.token-code-container {
  margin: 22px 0;
  border: 1px solid var(--color-rule);
  border-radius: 6px;
  overflow: hidden;
  background: #252422;
}

.token-code-header {
  background: #1c1b1a;
  padding: 8px 14px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid #383633;
}

.token-code-title {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: #a8a29e;
}

.token-code-hint {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  color: #d68361;
}

.token-code-body {
  padding: 16px;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 0.9rem;
  line-height: 1.8;
  color: #f4f0e6;
  overflow-x: auto;
}

.token-pill {
  display: inline-block;
  padding: 2px 6px;
  margin: 2px 1px;
  border-radius: 4px;
  background: #33312e;
  border: 1px solid #4a4742;
  cursor: pointer;
  transition: all 0.15s ease;
}

.token-pill:hover, .token-pill.active {
  background: #bd4d24;
  border-color: #e06c3f;
  color: #fff;
  box-shadow: 0 0 8px rgba(189, 77, 36, 0.4);
}

.token-keyword { color: #e59866; font-weight: 600; }
.token-ident { color: #85c1e9; }
.token-string { color: #a9dfbf; }
.token-func { color: #f9e79f; }

.token-explainer-deck {
  background: #1e1d1b;
  border-top: 1px solid #383633;
  padding: 14px 16px;
}

.token-explainer-item {
  font-family: var(--font-sans);
  font-size: 0.88rem;
  line-height: 1.5;
  color: #d6d3cb;
  display: none;
}

.token-explainer-item.active {
  display: block;
}

.token-explainer-item strong {
  color: #fff;
  font-weight: 700;
}

/* 3. Why Do I Care? Callout */
.why-care {
  background: #faf4ed;
  border-left: 4px solid var(--color-accent);
  padding: 16px 20px;
  margin: 22px 0;
  border-radius: 0 6px 6px 0;
  border-top: 1px solid #eee1d3;
  border-right: 1px solid #eee1d3;
  border-bottom: 1px solid #eee1d3;
}

.why-care-badge {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-accent);
  margin-bottom: 6px;
  display: inline-block;
}

.why-care-title {
  font-family: var(--font-display);
  font-size: 1.08rem;
  font-weight: 700;
  color: var(--color-ink);
  margin-bottom: 6px;
}

.why-care p {
  margin: 0;
  font-family: var(--font-body);
  font-size: 0.94rem;
  line-height: 1.6;
  color: var(--color-ink);
}

/* 4. Common Trap / Misconception Card */
.common-trap {
  background: var(--color-paper);
  border: 1px solid #e0c9bd;
  border-radius: 6px;
  margin: 24px 0;
  overflow: hidden;
}

.common-trap-header {
  background: #f7ebe4;
  padding: 10px 16px;
  display: flex;
  align-items: center;
  gap: 8px;
  border-bottom: 1px solid #e0c9bd;
}

.common-trap-badge {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: #a33816;
}

.common-trap-title {
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 700;
  color: #78260d;
}

.common-trap-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0;
}

.trap-col {
  padding: 16px 20px;
}

.trap-col.bad {
  background: #fdfaf7;
  border-right: 1px solid #e0c9bd;
}

.trap-col.good {
  background: #f5f9f6;
}

.trap-col-label {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.trap-col.bad .trap-col-label { color: #b03a2e; }
.trap-col.good .trap-col-label { color: #196f3d; }

.trap-col p {
  font-family: var(--font-body);
  font-size: 0.92rem;
  line-height: 1.55;
  margin: 0;
  color: var(--color-ink);
}

/* 5. Interactive X vs. Y Classifier */
.xy-selector {
  background: var(--color-paper-dark);
  border: 1px solid var(--color-rule);
  border-radius: 6px;
  padding: 18px 20px;
  margin: 20px 0;
}

.xy-prompt {
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--color-ink);
  margin-bottom: 12px;
}

.xy-columns {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 14px;
}

.xy-box {
  background: var(--color-paper);
  border: 2px dashed var(--color-rule);
  border-radius: 6px;
  padding: 14px;
  min-height: 110px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.xy-box.active {
  border-color: var(--color-accent);
  background: #fdf8f4;
}

.xy-box-title {
  font-family: var(--font-sans);
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-ink-light);
  display: flex;
  justify-content: space-between;
}

.xy-card-bank {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 14px;
}

.xy-pill {
  font-family: var(--font-sans);
  font-size: 0.82rem;
  padding: 6px 12px;
  background: var(--color-paper);
  border: 1px solid var(--color-rule);
  border-radius: 20px;
  cursor: pointer;
  user-select: none;
  transition: all 0.15s ease;
}

.xy-pill:hover {
  background: #eee6db;
  border-color: var(--color-ink-light);
}

.xy-pill.in-x {
  background: #ebf5fb;
  border-color: #85c1e9;
  color: #1b4f72;
  font-weight: 600;
}

.xy-pill.in-y {
  background: #fbeee6;
  border-color: #edbb99;
  color: #78281f;
  font-weight: 600;
}

/* 6. Cross-Validation Stepper Cards */
.cv-stepper {
  background: var(--color-paper);
  border: 1px solid var(--color-rule);
  border-radius: 6px;
  padding: 20px;
  margin: 22px 0;
}

.cv-tabs {
  display: flex;
  gap: 6px;
  margin-bottom: 16px;
  border-bottom: 1px solid var(--color-rule);
  padding-bottom: 10px;
  overflow-x: auto;
}

.cv-tab-btn {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 700;
  padding: 6px 14px;
  background: var(--color-paper-dark);
  border: 1px solid var(--color-rule);
  border-radius: 4px;
  cursor: pointer;
  color: var(--color-ink);
  transition: all 0.15s ease;
  white-space: nowrap;
}

.cv-tab-btn:hover {
  background: #ebe3d7;
}

.cv-tab-btn.active {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
}

.cv-patient-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
  gap: 10px;
  margin: 14px 0;
}

.cv-patient-card {
  padding: 10px 12px;
  border-radius: 4px;
  border: 1px solid var(--color-rule);
  font-family: var(--font-sans);
  font-size: 0.8rem;
  display: flex;
  flex-direction: column;
  gap: 4px;
  transition: all 0.2s ease;
}

.cv-patient-card.is-train {
  background: #eaf2f8;
  border-color: #aed6f1;
  color: #1b4f72;
}

.cv-patient-card.is-test {
  background: #fadbd8;
  border-color: #f5b7b1;
  color: #78281f;
  transform: scale(1.04);
  box-shadow: 0 2px 8px rgba(189, 77, 36, 0.25);
  font-weight: 700;
}

.cv-status-msg {
  padding: 12px 14px;
  background: var(--color-paper-dark);
  border-left: 3px solid var(--color-accent);
  font-family: var(--font-body);
  font-size: 0.92rem;
  margin-top: 14px;
  line-height: 1.55;
}

/* Narrative Bridge */
.narrative-bridge {
  background: linear-gradient(to right, #faf4ec, #f4eee2);
  border: 1px solid #dfd5c5;
  border-radius: 6px;
  padding: 18px 22px;
  margin: 28px 0 16px 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.narrative-bridge-text {
  font-family: var(--font-body);
  font-size: 0.96rem;
  line-height: 1.6;
  color: var(--color-ink);
}

.narrative-bridge-text strong {
  display: block;
  font-family: var(--font-display);
  font-size: 1.05rem;
  color: var(--color-ink);
  margin-bottom: 4px;
}

.narrative-bridge-btn {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 10px 18px;
  background: var(--color-accent);
  color: #fff;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  white-space: nowrap;
  text-decoration: none;
  transition: all 0.15s ease;
}

.narrative-bridge-btn:hover {
  background: #a33816;
  transform: translateX(3px);
}

/* Responsive adjustments for new components */
@media (max-width: 640px) {
  .common-trap-grid, .xy-columns {
    grid-template-columns: 1fr;
  }
  .trap-col.bad {
    border-right: none;
    border-bottom: 1px solid #e0c9bd;
  }
  .narrative-bridge {
    flex-direction: column;
    align-items: flex-start;
  }
}

/* Responsive Styles */
@media (max-width: 960px) {
  .app-layout {
    grid-template-columns: 1fr;
  }
  
  .sidebar {
    display: none;
    position: fixed;
    z-index: 100;
    top: 145px;
    left: 0;
    width: min(340px, 92vw);
    background: var(--color-paper);
    height: calc(100vh - 145px);
    border-right: 2px solid var(--color-rule);
    box-shadow: 10px 10px 30px rgba(0,0,0,0.15);
  }
  
  .sidebar.open {
    display: block;
  }
  
  .masthead__menu-btn {
    display: inline-flex;
  }
  
  nav.masthead__nav {
    flex-wrap: wrap;
  }
  
  .opening {
    grid-template-columns: 1fr;
  }
  
  .assumption-grid, .metric-grid {
    grid-template-columns: 1fr;
  }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    scroll-behavior: auto !important;
    transition: none !important;
  }
}