/* RAG for Everyone — shared style
   Based on the proven Python for Everyone glassmorphic course shell.
   Design goals: premium, attention-grabbing, architecture-friendly, and
   still clear enough for a first-time GenAI systems learner. */

:root {
  --color-bg: #F6F7FB;
  --color-text: #171A21;
  --color-text-soft: #4B5160;
  --color-navy: #101B33;
  --color-navy-2: #16274A;
  --color-blue: #2E6BB8;
  --color-blue-dark: #1B4F8C;
  --color-yellow: #FFC93C;
  --color-yellow-dark: #E6A800;
  --color-green: #1E8E3E;
  --color-red: #C5221F;
  --color-teal: #0E7C86;
  --color-card-bg: rgba(255, 255, 255, 0.62);
  --color-border: rgba(16, 27, 51, 0.10);
  --glass-blur: blur(18px);
  --glass-border: 1px solid rgba(255, 255, 255, 0.55);
  --shadow-sm: 0 2px 8px rgba(16, 27, 51, 0.06);
  --shadow-md: 0 10px 30px rgba(16, 27, 51, 0.10);
  --shadow-lg: 0 20px 50px rgba(16, 27, 51, 0.16);
  --radius: 14px;
  --max-width: 800px;
  --sidebar-width: 290px;
  --font-display: "Space Grotesk", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-body: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  padding: 0 0 0 var(--sidebar-width);
  position: relative;
  min-height: 100vh;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: 19px;
  line-height: 1.7;
}

/* Soft gradient-mesh backdrop for the glassmorphic surfaces to blur against */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(circle at 8% 12%, rgba(46, 107, 184, 0.30), transparent 38%),
    radial-gradient(circle at 92% 15%, rgba(255, 201, 60, 0.24), transparent 34%),
    radial-gradient(circle at 25% 92%, rgba(27, 79, 140, 0.26), transparent 42%),
    radial-gradient(circle at 85% 88%, rgba(16, 27, 51, 0.30), transparent 40%),
    linear-gradient(160deg, #EEF0F8 0%, #E4E9F6 50%, #EAEEF9 100%);
  background-attachment: fixed;
}

.page {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 32px 20px 80px;
}

/* ---------- Top navigation ---------- */
header.top-bar {
  background: rgba(16, 27, 51, 0.72);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  color: #fff;
  padding: 16px 20px;
  position: sticky;
  top: 0;
  z-index: 50;
  box-shadow: var(--shadow-md);
}

header.top-bar .page {
  padding: 0;
  max-width: 1080px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
}

header.top-bar a.brand {
  color: #fff;
  text-decoration: none;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 20px;
  letter-spacing: -0.01em;
}

header.top-bar nav a {
  color: #fff;
  font-weight: 500;
  font-size: 15px;
  margin-left: 20px;
  text-decoration: none;
  opacity: 0.85;
  transition: opacity 0.15s ease;
}

header.top-bar nav a:hover {
  opacity: 1;
  text-decoration: underline;
}

/* ---------- Typography ---------- */
h1 {
  font-family: var(--font-display);
  font-size: 38px;
  font-weight: 700;
  letter-spacing: -0.015em;
  color: var(--color-navy);
  margin-top: 0;
  line-height: 1.15;
}

h2 {
  font-family: var(--font-display);
  font-size: 27px;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--color-navy);
  margin-top: 56px;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 10px;
}

h2::after {
  content: "";
  flex: 1;
  height: 3px;
  background: linear-gradient(90deg, var(--color-yellow), transparent);
  border-radius: 2px;
  margin-left: 4px;
}

h3 {
  font-family: var(--font-display);
  font-size: 21px;
  font-weight: 700;
  color: var(--color-navy);
}

p, li {
  font-size: 19px;
  color: var(--color-text);
}

a {
  color: var(--color-blue);
}

strong {
  color: var(--color-navy);
}

/* ---------- Inline code / generic code blocks ---------- */
code, pre {
  font-family: "JetBrains Mono", "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
}

code {
  background: #EEF1F7;
  padding: 2px 7px;
  border-radius: 5px;
  font-size: 0.9em;
  color: var(--color-blue-dark);
}

pre {
  background: #0F1420;
  color: #E8ECF4;
  padding: 18px;
  border-radius: 10px;
  overflow-x: auto;
  font-size: 16px;
  line-height: 1.55;
  margin: 0;
}

pre code {
  background: none;
  padding: 0;
  color: inherit;
}

/* "Terminal window" wrapper for annotated code samples */
.code-window {
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow-md);
  margin: 20px 0;
}

.code-window-bar {
  background: #1B2233;
  padding: 10px 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.code-window-bar .dot {
  width: 11px;
  height: 11px;
  border-radius: 50%;
  display: inline-block;
}

.code-window-bar .dot.red { background: #FF5F56; }
.code-window-bar .dot.yellow { background: #FFBD2E; }
.code-window-bar .dot.green { background: #27C93F; }

.code-window-bar .filename {
  margin-left: 10px;
  color: #8A93A8;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 13px;
}

.code-window pre {
  border-radius: 0;
}

/* Output block — visually distinct from an input code window */
.output-block {
  margin: 12px 0 20px;
}

.output-block .output-label {
  display: inline-block;
  font-family: var(--font-display);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-green);
  background: #E7F6EA;
  padding: 3px 10px;
  border-radius: 999px;
  margin-bottom: 8px;
}

.output-block pre {
  background: #F4F6FA;
  color: #1B2233;
  border: 1px solid var(--color-border);
  border-radius: 10px;
}

/* ---------- Hero (landing page) ---------- */
.hero {
  background: radial-gradient(circle at 15% 20%, #1E3A66 0%, transparent 45%),
              linear-gradient(135deg, var(--color-navy) 0%, var(--color-navy-2) 55%, var(--color-blue-dark) 100%);
  color: #fff;
  padding: 72px 20px 84px;
}

.hero .page {
  padding-top: 0;
  padding-bottom: 0;
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(255, 201, 60, 0.14);
  border: 1px solid rgba(255, 201, 60, 0.35);
  color: var(--color-yellow);
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 13px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 6px 14px;
  border-radius: 999px;
  margin-bottom: 22px;
}

.hero h1 {
  color: #fff;
  font-size: 46px;
  max-width: 640px;
}

.hero p.lede {
  font-size: 21px;
  color: #C9D3E6;
  max-width: 560px;
  margin: 18px 0 30px;
}

.hero-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 34px;
}

.hero-badges span {
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.16);
  color: #E4E9F5;
  font-size: 14px;
  font-weight: 500;
  padding: 7px 14px;
  border-radius: 999px;
}

.btn-primary {
  display: inline-block;
  background: var(--color-yellow);
  color: var(--color-navy);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 17px;
  text-decoration: none;
  padding: 15px 28px;
  border-radius: 10px;
  box-shadow: 0 8px 24px rgba(255, 201, 60, 0.35);
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 30px rgba(255, 201, 60, 0.45);
}

.btn-secondary {
  display: inline-block;
  background: transparent;
  color: #fff;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 16px;
  text-decoration: none;
  padding: 14px 24px;
  border-radius: 10px;
  border: 1px solid rgba(255, 255, 255, 0.35);
  margin-left: 12px;
  transition: background 0.15s ease;
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.08);
}

.hero-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 36px;
  margin-top: 46px;
  padding-top: 28px;
  border-top: 1px solid rgba(255, 255, 255, 0.14);
}

.hero-stats div {
  display: flex;
  flex-direction: column;
}

.hero-stats strong {
  font-family: var(--font-display);
  font-size: 30px;
  font-weight: 700;
  color: var(--color-yellow);
  line-height: 1.1;
}

.hero-stats span {
  font-size: 13px;
  color: #9AA7C4;
  margin-top: 2px;
}

/* ---------- Feature grid ("why this course") ---------- */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 18px;
  margin: 24px 0 8px;
}

.feature-card {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 22px;
  box-shadow: var(--shadow-sm);
  transition: transform 0.18s ease, box-shadow 0.18s ease;
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.feature-card .icon {
  font-size: 28px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 52px;
  height: 52px;
  border-radius: 12px;
  background: linear-gradient(135deg, #EAF1FC, #DCE9FA);
  margin-bottom: 14px;
}

.feature-card h3 {
  margin: 0 0 6px;
  font-size: 18px;
}

.feature-card p {
  font-size: 16px;
  color: var(--color-text-soft);
  margin: 0;
}

/* ---------- Callout boxes (lesson pages) ---------- */
.hook {
  background: linear-gradient(135deg, var(--color-navy) 0%, var(--color-blue-dark) 100%);
  color: #fff;
  padding: 28px 30px;
  border-radius: 18px;
  font-size: 20px;
  box-shadow: 0 16px 40px rgba(16, 27, 51, 0.16);
  margin: 28px 0 24px;
  position: relative;
}

.hook::before {
  content: "🎯";
  font-size: 22px;
  margin-right: 10px;
}

.what-is {
  background: rgba(255, 248, 230, 0.65);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: 1px solid rgba(245, 223, 160, 0.7);
  border-left: 6px solid var(--color-yellow-dark);
  padding: 18px 22px;
  border-radius: 10px;
  margin: 22px 0;
  box-shadow: var(--shadow-sm);
}

.what-is .label {
  font-family: var(--font-display);
  font-weight: 700;
  color: var(--color-navy);
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 8px;
  font-size: 14px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.what-is .label::before {
  content: "📘";
  font-size: 16px;
}

.lesson-hero {
  background: linear-gradient(135deg, rgba(255, 255, 255, 0.95), rgba(234, 241, 252, 0.95));
  border: 1px solid rgba(16, 27, 51, 0.08);
  border-radius: 18px;
  padding: 24px 26px;
  margin: 24px 0 28px;
  box-shadow: 0 10px 30px rgba(16, 27, 51, 0.08);
}

.lesson-hero h2 {
  margin-top: 0;
  margin-bottom: 10px;
  font-size: 23px;
}

.lesson-hero h2::after {
  display: none;
}

.lesson-hero ul {
  margin: 10px 0 0 18px;
  padding: 0;
}

.lesson-stack {
  background: linear-gradient(135deg, rgba(234, 241, 252, 0.95), rgba(248, 250, 255, 0.95));
  border: 1px solid rgba(16, 27, 51, 0.08);
  border-left: 5px solid var(--color-blue);
  border-radius: 14px;
  padding: 16px 18px;
  margin: 20px 0;
  box-shadow: 0 8px 24px rgba(16, 27, 51, 0.06);
}

.lesson-pill {
  display: inline-block;
  font-family: var(--font-display);
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-blue-dark);
  background: #EAF1FC;
  padding: 4px 10px;
  border-radius: 999px;
  margin-bottom: 8px;
}

.lesson-bullets {
  margin: 0;
  padding-left: 20px;
}

.lesson-bullets li {
  margin-bottom: 6px;
}

.lesson-note {
  background: rgba(255, 248, 230, 0.72);
  border-left: 4px solid var(--color-yellow-dark);
  padding: 12px 14px;
  border-radius: 10px;
  margin: 16px 0;
}

.lesson-note strong {
  color: var(--color-navy);
}

/* Code walkthrough: annotated breakdown */
.code-breakdown {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 8px 22px 18px;
  margin: 18px 0;
  box-shadow: var(--shadow-sm);
}

.code-breakdown dt {
  font-family: "JetBrains Mono", monospace;
  background: linear-gradient(135deg, #EAF1FC, #DCE9FA);
  color: var(--color-blue-dark);
  display: inline-block;
  padding: 4px 10px;
  border-radius: 6px;
  margin-top: 16px;
  font-size: 15px;
  font-weight: 600;
}

.code-breakdown dd {
  margin: 8px 0 6px 0;
  color: var(--color-text-soft);
  font-size: 17px;
}

/* Go Deeper collapsible section */
details.go-deeper {
  background: rgba(240, 244, 251, 0.6);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 4px 22px 20px;
  margin: 26px 0;
}

details.go-deeper summary {
  cursor: pointer;
  font-family: var(--font-display);
  font-weight: 700;
  color: var(--color-blue-dark);
  padding: 16px 0;
  font-size: 18px;
  list-style: none;
}

details.go-deeper summary::-webkit-details-marker {
  display: none;
}

details.go-deeper summary::before {
  content: "🔬 ";
}

details.go-deeper summary::after {
  content: "▸";
  float: right;
  transition: transform 0.15s ease;
}

details.go-deeper[open] summary::after {
  transform: rotate(90deg);
}

details.go-deeper summary:hover {
  text-decoration: underline;
}

/* Points to Remember */
.points-to-remember {
  background: linear-gradient(135deg, rgba(234, 247, 236, 0.7), rgba(243, 251, 243, 0.65));
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: 1px solid rgba(190, 224, 190, 0.7);
  border-radius: var(--radius);
  padding: 8px 26px 20px;
  margin: 28px 0;
  box-shadow: var(--shadow-sm);
}

.points-to-remember h2 {
  border: none;
  margin-top: 14px;
}

.points-to-remember h2::before {
  content: "✅";
}

.points-to-remember h2::after {
  display: none;
}

.points-to-remember li {
  margin-bottom: 8px;
}

/* Chapter progress badge on lesson pages */
.chapter-badge {
  display: inline-block;
  font-family: var(--font-display);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--color-blue-dark);
  background: #EAF1FC;
  padding: 6px 14px;
  border-radius: 999px;
  margin-bottom: 14px;
}

/* ---------- Quiz elements ---------- */
.quiz-progress-wrap {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: 999px;
  height: 14px;
  overflow: hidden;
  margin: 8px 0 30px;
  box-shadow: inset 0 1px 3px rgba(16, 27, 51, 0.12);
}

.quiz-progress-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--color-blue), var(--color-yellow));
  border-radius: 999px;
  transition: width 0.35s ease;
}

.quiz-question {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px 28px;
  margin: 28px 0;
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.18s ease;
}

.quiz-question:hover {
  box-shadow: var(--shadow-md);
}

.quiz-question label {
  display: block;
  line-height: 1.65;
}

.q-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--color-navy);
  color: #fff;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 13px;
  vertical-align: middle;
  margin-right: 10px;
}

.fib-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin: 16px 0 0 36px;
}

.fib-blank {
  font-size: 18px;
  padding: 9px 12px;
  border: 2px solid var(--color-border);
  border-radius: 8px;
  min-width: 160px;
  max-width: 100%;
  font-family: "JetBrains Mono", monospace;
  transition: border-color 0.15s ease, background 0.15s ease;
}

.fib-blank.correct {
  border-color: var(--color-green);
  background: #E8F5E9;
}

.fib-blank.incorrect {
  border-color: var(--color-red);
  background: #FDECEA;
}

button.check-btn {
  font-family: var(--font-display);
  font-size: 15px;
  font-weight: 700;
  padding: 9px 18px;
  border: none;
  border-radius: 8px;
  background: var(--color-blue);
  color: #fff;
  cursor: pointer;
  transition: background 0.15s ease, transform 0.1s ease;
}

button.check-btn:hover {
  background: var(--color-blue-dark);
  transform: translateY(-1px);
}

button.check-btn:active {
  transform: translateY(0);
}

button.check-btn:focus-visible,
.fib-blank:focus-visible {
  outline: 3px solid var(--color-yellow);
  outline-offset: 2px;
}

.fib-feedback {
  font-weight: 700;
  font-size: 18px;
  min-width: 28px;
  display: inline-block;
}

.fib-feedback.correct { color: var(--color-green); }
.fib-feedback.incorrect { color: var(--color-red); }

/* ---------- Multiple-choice questions (Chapter 15 onward) ---------- */
.mcq-options {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin: 16px 0 0 36px;
}

.mcq-option {
  display: block;
  width: 100%;
  text-align: left;
  font-family: var(--font-body);
  font-size: 16px;
  padding: 12px 16px;
  border: 2px solid var(--color-border);
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.6);
  color: var(--color-text);
  cursor: pointer;
  transition: border-color 0.15s ease, background 0.15s ease, transform 0.1s ease;
}

.mcq-option:hover:not(:disabled) {
  border-color: var(--color-blue);
  background: rgba(46, 107, 184, 0.06);
}

.mcq-option:focus-visible {
  outline: 3px solid var(--color-yellow);
  outline-offset: 2px;
}

.mcq-option:disabled {
  cursor: default;
}

.mcq-option.correct {
  border-color: var(--color-green);
  background: #E8F5E9;
  color: var(--color-green);
  font-weight: 700;
}

.mcq-option.incorrect {
  border-color: var(--color-red);
  background: #FDECEA;
  color: var(--color-red);
  font-weight: 700;
}

.mcq-option.reveal-correct {
  border-color: var(--color-green);
  background: #E8F5E9;
  color: var(--color-green);
  font-weight: 700;
}

.mcq-feedback {
  display: block;
  margin: 12px 0 0 36px;
  font-weight: 700;
  font-size: 15px;
}

.mcq-feedback.correct { color: var(--color-green); }
.mcq-feedback.incorrect { color: var(--color-red); }

#check-all-wrap {
  margin-top: 24px;
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

#check-all-btn {
  background: var(--color-navy);
  padding: 13px 24px;
  font-size: 16px;
}

#check-all-btn:hover {
  background: #000;
}

#quiz-score {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 18px;
  color: var(--color-navy);
}

.quiz-celebration {
  display: none;
  margin-top: 22px;
  background: linear-gradient(135deg, #FFF3D6, #FFE7A8);
  border: 1px solid var(--color-yellow-dark);
  border-radius: var(--radius);
  padding: 20px 24px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 19px;
  color: var(--color-navy);
  box-shadow: var(--shadow-sm);
}

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

/* ---------- Nav buttons between chapter pages ---------- */
.chapter-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 56px;
  padding-top: 24px;
  border-top: 1px solid var(--color-border);
}

.chapter-nav a {
  font-family: var(--font-display);
  font-weight: 700;
  text-decoration: none;
  background: var(--color-blue);
  color: #fff;
  padding: 13px 22px;
  border-radius: 10px;
  box-shadow: var(--shadow-sm);
  transition: background 0.15s ease, transform 0.15s ease;
}

.chapter-nav a:hover {
  background: var(--color-blue-dark);
  transform: translateY(-2px);
}

/* ---------- Landing page chapter list ---------- */
.course-map {
  margin-top: 56px;
  width: min(1120px, calc(100vw - var(--sidebar-width) - 64px));
  margin-left: 50%;
  transform: translateX(-50%);
}

.section-heading-row,
.module-section-header {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 18px;
}

.section-kicker,
.module-kicker {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-display);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-teal);
  margin-bottom: 6px;
}

.module-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--module-accent);
  box-shadow: 0 0 0 5px color-mix(in srgb, var(--module-accent) 14%, transparent);
}

.section-link {
  color: var(--color-blue-dark);
  font-family: var(--font-display);
  font-weight: 700;
  text-decoration: none;
}

.section-link:hover {
  color: var(--color-teal);
}

.section-intro {
  max-width: 760px;
  color: var(--color-text-soft);
  margin: 10px 0 28px;
}

.module-list {
  display: grid;
  gap: 34px;
}

.module-section {
  --module-accent: var(--color-blue);
  position: relative;
  background:
    linear-gradient(135deg, color-mix(in srgb, var(--module-accent) 11%, transparent), rgba(255, 255, 255, 0.64) 38%),
    rgba(255, 255, 255, 0.58);
  border: 1px solid color-mix(in srgb, var(--module-accent) 20%, rgba(16, 27, 51, 0.10));
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: 0 18px 48px rgba(16, 27, 51, 0.10);
  overflow: hidden;
}

.module-section::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 5px;
  background: linear-gradient(180deg, var(--module-accent), color-mix(in srgb, var(--module-accent) 20%, transparent));
}

.module-section::after {
  content: "";
  position: absolute;
  right: -90px;
  top: -110px;
  width: 260px;
  height: 260px;
  border-radius: 50%;
  background: radial-gradient(circle, color-mix(in srgb, var(--module-accent) 18%, transparent), transparent 68%);
  pointer-events: none;
}

.module-section.module-2,
.chapter-card.module-2 { --module-accent: var(--color-teal); --card-accent: var(--color-teal); }
.module-section.module-3,
.chapter-card.module-3 { --module-accent: var(--color-green); --card-accent: var(--color-green); }
.module-section.module-4,
.chapter-card.module-4 { --module-accent: var(--color-navy-2); --card-accent: var(--color-navy-2); }
.module-section.module-5,
.chapter-card.module-5 { --module-accent: var(--color-yellow-dark); --card-accent: var(--color-yellow-dark); }
.module-section.module-6,
.chapter-card.module-6 { --module-accent: var(--color-blue-dark); --card-accent: var(--color-blue-dark); }
.module-section.module-7,
.chapter-card.module-7 { --module-accent: #8A5CF6; --card-accent: #8A5CF6; }
.module-section.module-8,
.chapter-card.module-8 { --module-accent: var(--color-navy); --card-accent: var(--color-navy); }

.module-section-header {
  position: relative;
  z-index: 1;
  align-items: flex-start;
  margin-bottom: 18px;
  padding-bottom: 16px;
  border-bottom: 1px solid color-mix(in srgb, var(--module-accent) 18%, rgba(16, 27, 51, 0.08));
}

.module-section-header h3 {
  margin: 0 0 6px;
  color: color-mix(in srgb, var(--module-accent) 34%, var(--color-navy));
}

.module-section-header p {
  max-width: 680px;
  margin: 0;
  color: var(--color-text-soft);
}

.module-status {
  flex-shrink: 0;
  background: color-mix(in srgb, var(--module-accent) 12%, #fff);
  border: 1px solid color-mix(in srgb, var(--module-accent) 28%, #fff);
  color: var(--module-accent);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 12px;
  padding: 6px 10px;
  border-radius: 999px;
}

.chapter-grid {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(235px, 1fr));
  gap: 18px;
}

.chapter-card {
  --card-accent: var(--color-blue);
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 8px;
  min-height: 228px;
  background:
    linear-gradient(160deg, rgba(255, 255, 255, 0.88), rgba(255, 255, 255, 0.58)),
    var(--color-card-bg);
  border: 1px solid color-mix(in srgb, var(--card-accent) 18%, rgba(16, 27, 51, 0.09));
  border-radius: 12px;
  padding: 18px 18px 16px;
  text-decoration: none;
  color: inherit;
  box-shadow: 0 10px 28px rgba(16, 27, 51, 0.08);
  overflow: hidden;
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}

.chapter-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  width: 4px;
  background: linear-gradient(180deg, var(--card-accent), color-mix(in srgb, var(--card-accent) 15%, transparent));
}

.chapter-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
  border-color: var(--card-accent);
}

.chapter-card-planned {
  background:
    linear-gradient(160deg, rgba(255, 255, 255, 0.68), rgba(255, 255, 255, 0.42)),
    rgba(255, 255, 255, 0.42);
}

.chapter-card-planned:hover {
  transform: translateY(-2px);
}

.chapter-card-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 4px;
}

.chapter-number-orb {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  border-radius: 14px;
  background:
    linear-gradient(135deg, color-mix(in srgb, var(--card-accent) 92%, #fff), color-mix(in srgb, var(--card-accent) 52%, var(--color-navy)));
  color: #fff;
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 800;
  box-shadow: 0 10px 22px color-mix(in srgb, var(--card-accent) 24%, transparent);
}

.chapter-card-status {
  background: color-mix(in srgb, var(--card-accent) 10%, #fff);
  border: 1px solid color-mix(in srgb, var(--card-accent) 26%, #fff);
  color: var(--card-accent);
  font-family: var(--font-display);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 4px 9px;
  border-radius: 999px;
}

.chapter-card-icon {
  font-size: 34px;
  line-height: 1;
  margin-bottom: 4px;
}

.chapter-card-num {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: color-mix(in srgb, var(--card-accent) 78%, var(--color-navy));
}

.chapter-card h3 {
  font-family: var(--font-display);
  font-size: 21px;
  line-height: 1.15;
  margin: 2px 0 2px;
  color: color-mix(in srgb, var(--card-accent) 28%, var(--color-navy));
}

.chapter-card p {
  font-size: 14px;
  line-height: 1.55;
  color: #3E4554;
  margin: 0 0 14px;
  flex-grow: 1;
}

.chapter-card-cta {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 14px;
  color: var(--card-accent);
}

.chapter-card-cta span {
  display: inline-block;
  transition: transform 0.18s ease;
}

.chapter-card:hover .chapter-card-cta span {
  transform: translateX(4px);
}

.chapter-card.chapter-complete {
  border-color: var(--color-green);
}

.chapter-card.chapter-complete::after {
  content: "✓ Completed";
  position: absolute;
  top: 14px;
  right: 16px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 11px;
  letter-spacing: 0.04em;
  color: var(--color-green);
  background: #E7F6EA;
  padding: 4px 10px;
  border-radius: 999px;
}

.chapter-card-more {
  --card-accent: var(--color-navy);
  background: linear-gradient(160deg, rgba(46, 107, 184, 0.08), rgba(16, 27, 51, 0.04));
  border-style: dashed;
}

.badge-coming-soon {
  color: var(--color-text-soft);
  font-style: italic;
}

/* ---------- Footer ---------- */
footer.site-footer {
  background: rgba(16, 27, 51, 0.75);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  color: #B7C0D6;
  padding: 32px 20px;
  margin-top: 60px;
  font-size: 15px;
}

footer.site-footer .page {
  padding: 0;
  max-width: 1080px;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
}

footer.site-footer a {
  color: #E4E9F5;
}

.footer-brand-credit {
  font-size: 13.5px;
  color: #8A93A8;
}

.footer-brand-credit a {
  color: #A9B4CC;
  font-weight: 600;
}

.footer-brand-credit a:hover {
  color: var(--color-yellow);
}

/* ---------- Page meta row (badges, reading time) ---------- */
.page-meta {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 14px;
}

.badge-difficulty {
  display: inline-block;
  font-family: var(--font-display);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--color-green);
  background: #E7F6EA;
  padding: 6px 14px;
  border-radius: 999px;
}

.reading-time {
  font-size: 15px;
  color: var(--color-text-soft);
}

.reading-time::before {
  content: "⏱ ";
}

/* ---------- On-this-page table of contents ---------- */
.page-toc {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 16px 18px;
  margin: 22px 0 32px;
  box-shadow: var(--shadow-sm);
}

.page-toc .toc-label {
  width: 100%;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-soft);
  margin-bottom: 4px;
}

.page-toc a {
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
  background: #EEF1F7;
  color: var(--color-blue-dark);
  padding: 6px 12px;
  border-radius: 999px;
  transition: background 0.15s ease;
}

.page-toc a:hover {
  background: #DCE9FA;
}

/* ---------- Download-file pills (exercises/project pages) ---------- */
.download-links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 18px 0 28px;
}

.download-links a {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 15px;
  text-decoration: none;
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  color: var(--color-navy);
  padding: 10px 16px;
  border-radius: 10px;
  box-shadow: var(--shadow-sm);
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.download-links a:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.download-links a::before {
  content: "⬇";
}

/* ---------- Exercise / project task cards ---------- */
.task-card {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px 24px;
  margin: 18px 0;
  box-shadow: var(--shadow-sm);
}

.task-card h3 {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 0;
}

.task-card .task-num {
  flex-shrink: 0;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--color-blue);
  color: #fff;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* ---------- Interview Q&A accordion ---------- */
.qa-item {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  margin: 16px 0;
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}

.qa-item summary {
  cursor: pointer;
  list-style: none;
  padding: 18px 22px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 18px;
  color: var(--color-navy);
  display: flex;
  align-items: center;
  gap: 12px;
}

.qa-item summary::-webkit-details-marker {
  display: none;
}

.qa-item summary::after {
  content: "▸";
  margin-left: auto;
  color: var(--color-blue);
  transition: transform 0.15s ease;
}

.qa-item[open] summary::after {
  transform: rotate(90deg);
}

.qa-item summary .q-num {
  background: var(--color-navy);
}

.qa-body {
  padding: 0 22px 22px;
}

.qa-section-label {
  display: inline-block;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 4px 10px;
  border-radius: 999px;
  margin: 14px 0 8px;
}

.qa-section-label.strong { background: #E7F6EA; color: var(--color-green); }
.qa-section-label.flags { background: #FCE9E8; color: var(--color-red); }
.qa-section-label.followup { background: #EAF1FC; color: var(--color-blue-dark); }

/* ---------- Roadmap page ---------- */
.roadmap-list {
  list-style: none;
  padding: 0;
  counter-reset: roadmap;
}

.roadmap-list li {
  display: flex;
  align-items: center;
  gap: 16px;
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 16px 22px;
  margin-bottom: 12px;
  box-shadow: var(--shadow-sm);
}

.roadmap-list li.built {
  border-left: 5px solid var(--color-green);
}

.roadmap-list li.planned {
  opacity: 0.75;
}

.roadmap-status {
  flex-shrink: 0;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  padding: 5px 12px;
  border-radius: 999px;
}

.roadmap-status.built { background: #E7F6EA; color: var(--color-green); }
.roadmap-status.planned { background: #EEF0F4; color: var(--color-text-soft); }

/* ---------- Progress badges (localStorage-driven) ---------- */
.complete-badge {
  display: inline-block;
  font-family: var(--font-display);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--color-green);
  background: #E7F6EA;
  padding: 4px 10px;
  border-radius: 999px;
  margin-left: 10px;
}

.roadmap-list li.chapter-complete .roadmap-status {
  background: #E7F6EA;
  color: var(--color-green);
}

/* ---------- Live code playground ---------- */
.playground {
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow-md);
  margin: 20px 0;
}

.playground-bar {
  background: #1B2233;
  padding: 10px 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  flex-wrap: wrap;
}

.playground-bar .filename {
  color: #8A93A8;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 13px;
}

.playground-run-btn {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 14px;
  background: var(--color-yellow);
  color: var(--color-navy);
  border: none;
  padding: 7px 16px;
  border-radius: 8px;
  cursor: pointer;
  transition: transform 0.12s ease;
}

.playground-run-btn:hover {
  transform: translateY(-1px);
}

.playground-run-btn:disabled {
  opacity: 0.7;
  cursor: wait;
}

.playground textarea.playground-code {
  display: block;
  width: 100%;
  border: none;
  resize: vertical;
  background: #0F1420;
  color: #E8ECF4;
  font-family: "JetBrains Mono", "SFMono-Regular", Consolas, monospace;
  font-size: 15px;
  line-height: 1.55;
  padding: 18px;
  min-height: 90px;
}

.playground textarea.playground-code:focus {
  outline: 2px solid var(--color-blue);
  outline-offset: -2px;
}

.playground-output {
  background: #F4F6FA;
  color: #1B2233;
  border-top: 1px solid var(--color-border);
  font-family: "JetBrains Mono", monospace;
  font-size: 14px;
  padding: 14px 18px;
  white-space: pre-wrap;
  min-height: 24px;
}

.playground-note {
  font-size: 14px;
  color: var(--color-text-soft);
  margin-top: 6px;
}

/* ---------- HackerRank-style coding challenges (auto-graded) ---------- */
.challenge-card {
  background: var(--color-card-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 22px 26px;
  margin: 24px 0;
  box-shadow: var(--shadow-md);
}

.challenge-card h3 {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 0;
}

.challenge-statement {
  margin: 10px 0 16px;
}

.challenge-statement .constraints,
.challenge-statement .examples {
  font-size: 16px;
  background: rgba(16, 27, 51, 0.04);
  border-radius: 10px;
  padding: 10px 16px;
  margin: 10px 0;
}

.challenge-statement code {
  font-family: "JetBrains Mono", "SFMono-Regular", Consolas, monospace;
}

textarea.challenge-code {
  display: block;
  width: 100%;
  border: none;
  resize: vertical;
  background: #0F1420;
  color: #E8ECF4;
  font-family: "JetBrains Mono", "SFMono-Regular", Consolas, monospace;
  font-size: 15px;
  line-height: 1.55;
  padding: 18px;
  min-height: 120px;
  border-radius: 12px;
}

textarea.challenge-code:focus {
  outline: 2px solid var(--color-blue);
  outline-offset: -2px;
}

.challenge-run-btn {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 14px;
  background: var(--color-yellow);
  color: var(--color-navy);
  border: none;
  padding: 9px 20px;
  border-radius: 8px;
  cursor: pointer;
  margin-top: 12px;
  transition: transform 0.12s ease;
}

.challenge-run-btn:hover {
  transform: translateY(-1px);
}

.challenge-run-btn:disabled {
  opacity: 0.7;
  cursor: wait;
}

.challenge-results {
  margin-top: 14px;
}

.challenge-case {
  font-family: "JetBrains Mono", monospace;
  font-size: 13.5px;
  padding: 8px 14px;
  border-radius: 8px;
  margin-bottom: 6px;
  line-height: 1.5;
}

.challenge-case.pass {
  background: rgba(30, 142, 62, 0.10);
  color: #14532D;
}

.challenge-case.fail {
  background: rgba(197, 34, 31, 0.08);
  color: #7A1613;
}

.challenge-summary {
  font-family: var(--font-display);
  font-weight: 700;
  margin-top: 10px;
  color: var(--color-text-soft);
}

.challenge-summary.all-pass {
  color: var(--color-green);
}

/* ---------- Sub-topic quick recap (lighter than Points to Remember) ---------- */
.quick-recap {
  background: #F4F8F4;
  border: 1px dashed #A9CFA9;
  border-radius: 10px;
  padding: 14px 20px;
  margin: 20px 0 32px;
  font-size: 17px;
}

.quick-recap .label {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--color-green);
  display: block;
  margin-bottom: 6px;
}

.quick-recap .label::before {
  content: "📌 ";
}

.quick-recap ul {
  margin: 4px 0 0;
  padding-left: 22px;
}

.quick-recap li {
  font-size: 16px;
  margin-bottom: 4px;
}

/* ---------- Sub-topic section divider ---------- */
.subtopic {
  margin-top: 44px;
  padding-top: 4px;
}

.subtopic-label {
  display: inline-block;
  font-family: var(--font-display);
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-blue-dark);
  background: #EAF1FC;
  padding: 4px 12px;
  border-radius: 999px;
  margin-bottom: 10px;
}

/* ---------- Debug-the-code exercise cards ---------- */
.debug-card {
  background: rgba(255, 244, 243, 0.65);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: 1px solid rgba(243, 198, 194, 0.7);
  border-left: 6px solid var(--color-red);
  border-radius: var(--radius);
  padding: 20px 24px;
  margin: 18px 0;
}

.debug-card h3 {
  margin-top: 0;
  color: var(--color-red);
}

/* ---------- Scenario-based (interview-style) practice cards ---------- */
.scenario-card {
  background: rgba(232, 246, 247, 0.65);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: 1px solid rgba(14, 124, 134, 0.25);
  border-left: 6px solid var(--color-teal);
  border-radius: var(--radius);
  padding: 20px 24px;
  margin: 18px 0;
}

.scenario-card h3 {
  margin-top: 0;
  color: var(--color-teal);
}

.scenario-card .scenario-tag {
  display: inline-block;
  font-family: var(--font-display);
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: #fff;
  background: var(--color-teal);
  padding: 3px 10px;
  border-radius: 999px;
  margin-bottom: 10px;
}

/* ---------- Tables ---------- */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 20px 0;
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

th, td {
  text-align: left;
  padding: 12px 18px;
  font-size: 17px;
}

th {
  background: var(--color-navy);
  color: #fff;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 15px;
}

td {
  border-top: 1px solid var(--color-border);
}

tbody tr:nth-child(even) {
  background: #F7F8FC;
}

/* ---------- Glass blur for the remaining card-style components ---------- */
.feature-card,
.code-breakdown,
.quiz-progress-wrap,
.quiz-question,
.chapter-card,
.page-toc,
.task-card,
.scenario-card,
.qa-item,
.roadmap-list li,
table {
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
}

/* ---------- "In the Real World" callout ---------- */
.real-world {
  background: rgba(14, 124, 134, 0.10);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: 1px solid rgba(14, 124, 134, 0.28);
  border-left: 6px solid var(--color-teal);
  border-radius: var(--radius);
  padding: 20px 24px;
  margin: 28px 0;
}

.real-world .label {
  font-family: var(--font-display);
  font-weight: 700;
  color: var(--color-teal);
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 8px;
  font-size: 14px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.real-world .label::before {
  content: "🌍";
  font-size: 16px;
}

.real-world ul {
  margin: 6px 0 0;
  padding-left: 22px;
}

.real-world li {
  margin-bottom: 6px;
}

/* ---------- Sidebar: persistent digital-textbook chapter navigation ---------- */
.sidebar-toggle {
  display: none;
  position: fixed;
  top: 14px;
  left: 14px;
  z-index: 200;
  background: rgba(16, 27, 51, 0.85);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  color: #fff;
  border: 1px solid rgba(255, 255, 255, 0.15);
  border-radius: 10px;
  padding: 10px 16px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 14px;
  cursor: pointer;
}

.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  height: 100vh;
  width: var(--sidebar-width);
  overflow-y: auto;
  background: rgba(16, 27, 51, 0.68);
  backdrop-filter: blur(26px);
  -webkit-backdrop-filter: blur(26px);
  border-right: 1px solid rgba(255, 255, 255, 0.08);
  padding: 20px 14px 40px;
  z-index: 150;
  transition: transform 0.25s ease;
  scrollbar-width: thin;
}

.sidebar-brand {
  display: block;
  color: #fff;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 18px;
  text-decoration: none;
  margin-bottom: 6px;
  padding: 4px 8px;
}

.sidebar-subtitle {
  display: block;
  color: #8A93A8;
  font-size: 12px;
  padding: 0 8px 16px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  margin-bottom: 12px;
}

.sidebar-module {
  margin-bottom: 4px;
}

.sidebar-module summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  cursor: pointer;
  list-style: none;
  color: #C9D3E6;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 10px 8px;
  border-radius: 8px;
}

.sidebar-module summary span {
  min-width: 0;
}

.sidebar-module summary em {
  color: var(--color-yellow);
  font-style: normal;
  font-size: 11px;
  letter-spacing: 0;
  background: rgba(255, 201, 60, 0.11);
  border: 1px solid rgba(255, 201, 60, 0.22);
  border-radius: 999px;
  padding: 2px 7px;
}

.sidebar-module summary::-webkit-details-marker {
  display: none;
}

.sidebar-module summary:hover {
  background: rgba(255, 255, 255, 0.06);
}

.sidebar-module summary::after {
  content: "▸";
  flex-shrink: 0;
  color: #6B7C9C;
  transition: transform 0.15s ease;
}

.sidebar-module[open] summary::after {
  transform: rotate(90deg);
}

.sidebar-chapter-list {
  list-style: none;
  padding: 0;
  margin: 2px 0 10px;
}

.sidebar-chapter-list li a,
.sidebar-chapter-list li .soon {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 10px;
  border-radius: 8px;
  font-size: 14px;
  line-height: 1.3;
  color: #E4E9F5;
  text-decoration: none;
}

.sidebar-chapter-list li a span:not(.sidebar-check),
.sidebar-chapter-list li .soon span {
  min-width: 0;
}

.sidebar-chapter-list li a em,
.sidebar-chapter-list li .soon em {
  margin-left: auto;
  flex-shrink: 0;
  font-style: normal;
  font-size: 10px;
  font-family: var(--font-display);
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  border-radius: 999px;
  padding: 2px 6px;
}

.sidebar-chapter-list li.live a em {
  color: #3ED07C;
  background: rgba(62, 208, 124, 0.1);
}

.sidebar-chapter-list li.planned .soon em {
  color: #6B7C9C;
  background: rgba(255, 255, 255, 0.05);
}

.sidebar-chapter-list li a:hover {
  background: rgba(255, 255, 255, 0.08);
}

.sidebar-chapter-list li.active a {
  background: rgba(255, 201, 60, 0.18);
  color: var(--color-yellow);
  font-weight: 700;
}

.sidebar-chapter-list li .soon {
  color: #5E6C89;
  cursor: default;
}

.sidebar-check {
  color: #3ED07C;
  flex-shrink: 0;
}

.sidebar-subtopic-list {
  list-style: none;
  margin: 0 0 4px;
  padding: 0 0 0 26px;
  border-left: 1px solid rgba(255, 255, 255, 0.08);
  margin-left: 18px;
}

.sidebar-subtopic-list li a {
  display: block;
  padding: 5px 8px;
  border-radius: 6px;
  font-size: 12.5px;
  line-height: 1.3;
  color: #8A93A8;
  text-decoration: none;
}

.sidebar-subtopic-list li a:hover {
  background: rgba(255, 255, 255, 0.06);
  color: #E4E9F5;
}

.sidebar-scrim {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.4);
  z-index: 140;
}

.sidebar-exam-link {
  display: block;
  padding: 6px 10px 10px 34px;
  font-size: 13px;
  color: #9AA7C4;
  text-decoration: none;
}

.sidebar-exam-link:hover {
  color: var(--color-yellow);
}

/* ---------- Responsive ---------- */
@media (max-width: 640px) {
  body { font-size: 17px; }
  .hero h1 { font-size: 32px; }
  .hero p.lede { font-size: 18px; }
  h1 { font-size: 28px; }
  h2 { font-size: 22px; }
  .btn-secondary { margin-left: 0; margin-top: 10px; }
  .course-map {
    width: calc(100vw - 32px);
  }
  .section-heading-row,
  .module-section-header {
    align-items: flex-start;
    flex-direction: column;
  }
  .module-section {
    padding: 18px;
  }
  .chapter-grid {
    grid-template-columns: 1fr;
  }
  .chapter-card {
    min-height: 0;
  }

  .quiz-question { padding: 18px 18px; }
  .quiz-question label { font-size: 15px; gap: 10px; }
  .q-num { width: 26px; height: 26px; font-size: 12px; }
  .fib-row {
    flex-direction: column;
    align-items: stretch;
    margin-left: 0;
    margin-top: 14px;
    gap: 8px;
  }
  .fib-blank { min-width: 0; width: 100%; }
  button.check-btn { width: 100%; }
  .fib-feedback { text-align: center; }

  .mcq-options { margin-left: 0; }
  .mcq-feedback { margin-left: 0; text-align: center; }
}

@media (max-width: 900px) {
  body { padding-left: 0; }
  .course-map {
    width: min(1120px, calc(100vw - 40px));
  }
  .sidebar {
    transform: translateX(-100%);
    box-shadow: var(--shadow-lg);
  }
  .sidebar.open {
    transform: translateX(0);
  }
  .sidebar-toggle {
    display: block;
  }
  .sidebar-scrim.show {
    display: block;
  }
}

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

/* RAG for Everyone identity layer
   Keep the Python for Everyone glassmorphic system intact; only adapt the
   palette and course mark for retrieval, architecture, and GenAI learning. */
:root {
  --color-bg: #F4F8FA;
  --color-text: #172326;
  --color-text-soft: #536A70;
  --color-navy: #101B33;
  --color-navy-2: #152942;
  --color-blue: #0E7C86;
  --color-blue-dark: #095B63;
  --color-yellow: #FFC93C;
  --color-yellow-dark: #C28A00;
  --color-teal: #13A7B5;
}

body::before {
  background:
    radial-gradient(circle at 8% 12%, rgba(14, 124, 134, 0.30), transparent 38%),
    radial-gradient(circle at 92% 15%, rgba(255, 201, 60, 0.24), transparent 34%),
    radial-gradient(circle at 25% 92%, rgba(19, 167, 181, 0.24), transparent 42%),
    radial-gradient(circle at 85% 88%, rgba(16, 27, 51, 0.30), transparent 40%),
    linear-gradient(160deg, #EEF8F9 0%, #E6EEF5 50%, #F4F8FA 100%);
}

.brand::before,
.sidebar-brand::before {
  content: "";
  display: inline-block;
  width: 24px;
  height: 24px;
  margin-right: 8px;
  vertical-align: -6px;
  background: url("rag-mark.svg") center / contain no-repeat;
}

.hero {
  background:
    radial-gradient(circle at 15% 20%, rgba(19, 167, 181, 0.32) 0%, transparent 45%),
    radial-gradient(circle at 78% 18%, rgba(255, 201, 60, 0.18), transparent 32%),
    linear-gradient(135deg, var(--color-navy) 0%, var(--color-navy-2) 55%, #064F58 100%);
}

.hook::before {
  content: "◇";
  color: var(--color-yellow);
}

.what-is .label::before {
  content: "Lens";
  color: var(--color-blue-dark);
}

.diagram-figure {
  margin: 28px 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-card-bg);
  overflow: hidden;
  box-shadow: var(--shadow-md);
}

.diagram-figure img {
  display: block;
  width: 100%;
  height: auto;
}

.diagram-figure figcaption {
  padding: 12px 16px;
  color: var(--color-text-soft);
  border-top: 1px solid var(--color-border);
  font-size: 15px;
}

.diagram-card {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 18px 22px;
  margin: 22px 0;
  box-shadow: var(--shadow-sm);
}

/* Rich architecture pattern cards for comparison-heavy lessons */
.rag-type-stack {
  display: grid;
  gap: 22px;
  margin: 26px 0;
}

.rag-type-card {
  position: relative;
  overflow: hidden;
  background:
    linear-gradient(135deg, rgba(255, 255, 255, 0.78), rgba(234, 241, 252, 0.68)),
    var(--color-card-bg);
  border: 1px solid rgba(16, 27, 51, 0.10);
  border-radius: 14px;
  padding: 22px;
  box-shadow: 0 14px 34px rgba(16, 27, 51, 0.10);
}

.rag-type-card::before {
  content: "";
  position: absolute;
  inset: 0 0 auto;
  height: 5px;
  background: linear-gradient(90deg, var(--color-blue), var(--color-yellow));
}

.rag-type-top {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 14px;
  align-items: start;
  margin-bottom: 14px;
}

.type-number {
  display: inline-flex;
  width: 44px;
  height: 44px;
  align-items: center;
  justify-content: center;
  border-radius: 12px;
  background: var(--color-navy);
  color: var(--color-yellow);
  font-family: var(--font-display);
  font-size: 14px;
  font-weight: 800;
  box-shadow: var(--shadow-sm);
}

.rag-type-top h3 {
  margin: 0 0 4px;
  font-size: 24px;
}

.rag-type-top p {
  margin: 0;
  color: var(--color-text-soft);
  font-size: 17px;
  line-height: 1.55;
}

.rag-flow {
  background: #101B33;
  color: #EEF4FF;
  border-radius: 10px;
  padding: 12px 14px;
  margin: 14px 0;
  font-family: "JetBrains Mono", "SFMono-Regular", Consolas, monospace;
  font-size: 14px;
  line-height: 1.6;
  overflow-x: auto;
}

.rag-flow span {
  color: var(--color-yellow);
  font-weight: 800;
  padding: 0 4px;
}

.rag-fit {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 14px 0 18px;
}

.rag-fit span {
  display: inline-flex;
  align-items: center;
  min-height: 30px;
  padding: 4px 10px;
  border-radius: 999px;
  background: rgba(46, 107, 184, 0.10);
  border: 1px solid rgba(46, 107, 184, 0.20);
  color: var(--color-blue-dark);
  font-size: 13px;
  font-weight: 700;
}

.rag-type-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(220px, 0.75fr);
  gap: 18px;
  align-items: start;
}

.rag-type-card h4 {
  margin: 0 0 6px;
  color: var(--color-navy);
  font-family: var(--font-display);
  font-size: 15px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.rag-type-card p {
  font-size: 16px;
  line-height: 1.65;
}

.quality-panel {
  background: rgba(255, 248, 230, 0.72);
  border: 1px solid rgba(230, 168, 0, 0.22);
  border-radius: 10px;
  padding: 14px;
}

.quality-row {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  padding: 9px 0;
  border-top: 1px solid rgba(16, 27, 51, 0.08);
  font-size: 14px;
}

.quality-row:first-of-type {
  border-top: 0;
}

.quality-row span {
  color: var(--color-text-soft);
}

.quality-row strong {
  text-align: right;
  color: var(--color-navy);
}

.pros-cons {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin-top: 16px;
}

.pros-cons > div {
  background: rgba(255, 255, 255, 0.58);
  border: 1px solid rgba(16, 27, 51, 0.08);
  border-radius: 10px;
  padding: 14px 16px;
}

.pros-cons ul {
  margin: 0;
  padding-left: 18px;
}

.pros-cons li {
  margin-bottom: 6px;
  font-size: 15px;
  line-height: 1.55;
}

.mentor-note {
  margin: 20px 0 24px;
  padding: 16px 18px;
  border-radius: 12px;
  border: 1px solid rgba(46, 107, 184, 0.16);
  border-left: 5px solid var(--color-blue);
  background: rgba(234, 241, 252, 0.78);
  color: var(--color-text);
  font-size: 17px;
  line-height: 1.65;
}

.field-depth {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin-top: 16px;
}

.field-depth > div {
  background: rgba(240, 244, 251, 0.72);
  border: 1px solid rgba(16, 27, 51, 0.08);
  border-radius: 10px;
  padding: 14px;
}

.field-depth p,
.field-depth li {
  font-size: 15px;
  line-height: 1.58;
}

.field-depth p {
  margin: 0;
}

.field-depth ul {
  margin: 0;
  padding-left: 18px;
}

.architect-note {
  border-left: 4px solid var(--color-blue);
  background: rgba(234, 241, 252, 0.72);
  border-radius: 10px;
  padding: 12px 14px;
  margin: 16px 0 0;
}

.production-depth-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin: 24px 0;
}

.depth-panel {
  background: rgba(255, 255, 255, 0.68);
  border: 1px solid rgba(16, 27, 51, 0.10);
  border-radius: 14px;
  padding: 18px;
  box-shadow: var(--shadow-sm);
}

.depth-panel span {
  display: inline-block;
  margin-bottom: 8px;
  color: var(--color-blue-dark);
  font-family: var(--font-display);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.depth-panel h3 {
  margin: 0 0 8px;
  font-size: 20px;
}

.depth-panel p {
  margin: 0;
  color: var(--color-text-soft);
  font-size: 16px;
  line-height: 1.65;
}

.case-study-card {
  background:
    linear-gradient(135deg, rgba(16, 27, 51, 0.96), rgba(27, 79, 140, 0.92)),
    var(--color-navy);
  border-radius: 16px;
  padding: 22px;
  box-shadow: var(--shadow-lg);
}

.case-study-card h3,
.case-study-card strong {
  color: #fff;
}

.case-study-card h3 {
  margin: 0 0 10px;
}

.case-study-card p,
.case-study-card li {
  color: #E5ECFA;
  font-size: 16px;
  line-height: 1.65;
}

.case-study-card ul {
  margin: 12px 0;
  padding-left: 20px;
}

.mistake-catalog {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin: 24px 0;
}

.mistake-card {
  position: relative;
  background: rgba(255, 255, 255, 0.72);
  border: 1px solid rgba(16, 27, 51, 0.10);
  border-radius: 12px;
  padding: 18px;
  box-shadow: var(--shadow-sm);
}

.mistake-card::before {
  content: "";
  position: absolute;
  inset: 0 0 auto;
  height: 4px;
  border-radius: 12px 12px 0 0;
  background: linear-gradient(90deg, var(--color-red), var(--color-yellow));
}

.mistake-id {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 36px;
  height: 30px;
  margin-bottom: 10px;
  border-radius: 999px;
  background: rgba(197, 34, 31, 0.10);
  color: var(--color-red);
  font-family: var(--font-display);
  font-size: 12px;
  font-weight: 800;
}

.mistake-card h3 {
  margin: 0 0 10px;
  font-size: 18px;
  line-height: 1.35;
}

.mistake-card div {
  padding-top: 8px;
  margin-top: 8px;
  border-top: 1px solid rgba(16, 27, 51, 0.08);
  color: var(--color-text-soft);
  font-size: 15px;
  line-height: 1.6;
}

.mistake-card div:first-of-type {
  border-top: 0;
  margin-top: 0;
  padding-top: 0;
}

.mistake-card strong {
  color: var(--color-navy);
}

/* Premium decision framework board */
.decision-board {
  position: relative;
  margin: 26px 0;
  padding: 22px;
  border-radius: 16px;
  border: 1px solid rgba(16, 27, 51, 0.10);
  background:
    linear-gradient(135deg, rgba(16, 27, 51, 0.94), rgba(27, 79, 140, 0.88)),
    var(--color-navy);
  box-shadow: 0 18px 46px rgba(16, 27, 51, 0.18);
  overflow: hidden;
}

.decision-board::before {
  content: "";
  position: absolute;
  inset: auto -20% -40% 30%;
  height: 220px;
  background: radial-gradient(circle, rgba(255, 201, 60, 0.24), transparent 64%);
  pointer-events: none;
}

.decision-north-star {
  position: relative;
  background: rgba(255, 255, 255, 0.10);
  border: 1px solid rgba(255, 255, 255, 0.16);
  border-radius: 12px;
  padding: 18px;
  margin-bottom: 18px;
}

.decision-label {
  display: inline-block;
  margin-bottom: 8px;
  padding: 4px 10px;
  border-radius: 999px;
  background: rgba(255, 201, 60, 0.18);
  color: var(--color-yellow);
  font-family: var(--font-display);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.decision-north-star strong {
  display: block;
  color: #fff;
  font-family: var(--font-display);
  font-size: 24px;
  line-height: 1.3;
}

.decision-north-star p {
  max-width: 680px;
  margin: 8px 0 0;
  color: #D9E3F6;
  font-size: 16px;
}

.decision-path {
  position: relative;
  display: grid;
  gap: 14px;
}

.decision-path::before {
  content: "";
  position: absolute;
  left: 23px;
  top: 12px;
  bottom: 12px;
  width: 2px;
  background: linear-gradient(180deg, var(--color-yellow), rgba(255, 255, 255, 0.20));
}

.decision-step {
  position: relative;
  display: grid;
  grid-template-columns: 48px 1fr;
  gap: 14px;
  align-items: start;
  padding: 16px;
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.93);
  border: 1px solid rgba(255, 255, 255, 0.62);
  box-shadow: 0 10px 26px rgba(16, 27, 51, 0.12);
}

.decision-step-num {
  position: relative;
  z-index: 1;
  display: inline-flex;
  width: 48px;
  height: 48px;
  align-items: center;
  justify-content: center;
  border-radius: 14px;
  background: #101B33;
  color: var(--color-yellow);
  font-family: var(--font-display);
  font-size: 13px;
  font-weight: 800;
}

.decision-step h3 {
  margin: 0 0 6px;
  font-size: 20px;
}

.decision-step p {
  margin: 0;
  font-size: 16px;
  line-height: 1.55;
}

.decision-if {
  color: var(--color-text-soft);
}

.decision-choice {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin: 12px 0;
}

.decision-choice span {
  padding: 3px 9px;
  border-radius: 999px;
  background: rgba(46, 107, 184, 0.10);
  color: var(--color-blue-dark);
  font-size: 12px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.decision-choice strong {
  color: var(--color-navy);
  font-family: var(--font-display);
  font-size: 18px;
}

.decision-proof {
  padding-left: 12px;
  border-left: 3px solid rgba(46, 107, 184, 0.28);
  color: var(--color-text);
}

.risk-step .decision-step-num {
  background: #3B1F1F;
  color: #FFD7D7;
}

.risk-step .decision-choice span {
  background: rgba(197, 34, 31, 0.10);
  color: var(--color-red);
}

.action-step .decision-step-num {
  background: #17332A;
  color: #C8F5D2;
}

.action-step .decision-choice span {
  background: rgba(30, 142, 62, 0.10);
  color: var(--color-green);
}

.decision-upgrades {
  position: relative;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin-top: 18px;
}

.decision-upgrades div {
  background: rgba(255, 248, 230, 0.94);
  border: 1px solid rgba(255, 201, 60, 0.34);
  border-radius: 12px;
  padding: 16px;
}

.decision-upgrades span {
  display: block;
  color: var(--color-text-soft);
  font-size: 13px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.decision-upgrades strong {
  display: block;
  margin: 4px 0 6px;
  color: var(--color-navy);
  font-family: var(--font-display);
  font-size: 18px;
}

.decision-upgrades p {
  margin: 0;
  font-size: 15px;
  line-height: 1.55;
  color: var(--color-text);
}

@media (max-width: 760px) {
  .rag-type-card {
    padding: 18px;
  }

  .rag-type-top,
  .rag-type-grid,
  .pros-cons,
  .field-depth,
  .production-depth-grid {
    grid-template-columns: 1fr;
  }

  .type-number {
    width: 38px;
    height: 38px;
  }

  .decision-board {
    padding: 16px;
  }

  .decision-north-star strong {
    font-size: 20px;
  }

  .decision-path::before {
    display: none;
  }

  .decision-step,
  .decision-upgrades,
  .mistake-catalog {
    grid-template-columns: 1fr;
  }
}