:root {
  color-scheme: dark;
  --font-display: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-body: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-reading: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-ui: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, "SFMono-Regular", Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  --bg: #050b14;
  --bg-alt: #071320;
  --surface: rgba(255, 255, 255, 0.06);
  --surface-strong: rgba(255, 255, 255, 0.10);
  --panel: rgba(255, 255, 255, 0.06);
  --panel-2: rgba(255, 255, 255, 0.10);
  --line: rgba(255, 255, 255, 0.16);
  --text: #eef7ff;
  --muted: #a8bbcb;
  --muted-strong: #cad9e6;
  --cyan: #67e8f9;
  --blue: #38bdf8;
  --blue-deep: #2563eb;
  --green: #22c55e;
  --amber: #f59e0b;
  --white: #ffffff;
  --accent: var(--cyan);
  --accent-2: var(--blue-deep);
  --shadow: 0 24px 80px rgba(0, 0, 0, 0.40);
  --radius: 8px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: var(--font-body);
  background: var(--bg);
  color: var(--text);
  line-height: 1.55;
}

body.graphic-zoom-active {
  overflow: hidden;
}

.wrap {
  max-width: none;
  margin: 0 auto;
  padding: 20px;
}

.main-content.course-layout {
  width: 100%;
  max-width: none;
  margin: 0;
  padding: 20px;
  display: grid;
  grid-template-columns: minmax(230px, 280px) minmax(0, 1fr);
  gap: 16px;
  align-items: start;
}

.main-content.course-layout .wrap {
  max-width: none;
  margin: 0;
  padding: 0;
}

.course-nav-pane {
  position: sticky;
  top: 14px;
  align-self: start;
}

.course-nav-title {
  margin: 0 0 10px;
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: 0.86rem;
  font-weight: 400;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  text-shadow: 0 0 18px rgba(103, 232, 249, 0.28);
}

.course-nav-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 5px;
}

.course-nav-link {
  display: block;
  border-radius: var(--radius);
  border: 1px solid transparent;
  padding: 8px 10px;
  color: var(--text);
  text-decoration: none;
  line-height: 1.35;
  font-size: 14px;
  transition: border-color 0.18s ease, background 0.18s ease, color 0.18s ease;
}

.course-nav-link:hover {
  background: rgba(255, 255, 255, 0.078);
  border-color: rgba(103, 232, 249, 0.34);
}

.course-nav-link.current {
  background: rgba(37, 99, 235, 0.34);
  border-color: rgba(103, 232, 249, 0.70);
  color: var(--white);
  font-weight: 700;
}

.card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
  margin-bottom: 14px;
  box-shadow: 0 14px 50px rgba(0, 0, 0, 0.18);
}

.title-card {
  text-align: center;
  border-color: rgba(56, 189, 248, 0.30);
  background: rgba(255, 255, 255, 0.055);
  box-shadow: var(--shadow);
}

.title-card-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

.hidden {
  display: none !important;
}

.code-example-card-hidden {
  display: none !important;
}

.code-example-card-user-hidden {
  display: none !important;
}

.graphic-card {
  padding: 0;
  margin: 0 0 14px;
  border: 1px solid var(--line);
  background: var(--panel);
  box-shadow: var(--shadow);
  overflow: hidden;
  line-height: 0;
  transition: margin 160ms ease, padding 160ms ease, border-radius 160ms ease;
}

.module-graphic {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 0;
  cursor: zoom-in;
}

.module-graphic:focus-visible {
  outline: 3px solid rgba(103, 232, 249, 0.86);
  outline-offset: 3px;
}

.graphic-card.is-expanded {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  max-width: none;
  margin: 0;
  padding: 0;
  border: 0;
  border-radius: 0;
  background: var(--bg);
  box-shadow: none;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 10000;
}

.graphic-card.is-expanded .module-graphic {
  width: 100%;
  height: 100%;
  max-width: 100vw;
  max-height: 100vh;
  object-fit: contain;
  border-radius: 0;
  cursor: zoom-out;
}

.badge {
  display: inline-block;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  background: rgba(103, 232, 249, 0.14);
  border: 1px solid rgba(103, 232, 249, 0.34);
  color: var(--cyan);
  padding: 4px 9px;
  border-radius: 999px;
  font-weight: 700;
  margin-bottom: 8px;
}

h1, h2 {
  margin: 0 0 8px;
  line-height: 1.2;
  letter-spacing: 0;
}

h1 {
  color: var(--white);
  font-family: var(--font-mono);
  font-weight: 400;
  font-size: clamp(1.8rem, 2.4vw, 3rem);
  text-shadow: 0 0 18px rgba(56, 189, 248, 0.24);
}

h2 {
  color: var(--text);
  font-family: var(--font-ui);
  font-size: 1.15rem;
  font-weight: 700;
}

.meta, .status {
  color: var(--muted);
  margin: 0;
}

.meta {
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.status {
  color: var(--muted);
  font-size: 0.9rem;
}

.nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 8px;
  margin-top: 12px;
}

button, .btn {
  border: 1px solid rgba(255, 255, 255, 0.24);
  border-radius: 999px;
  padding: 9px 12px;
  cursor: pointer;
  font-family: var(--font-ui);
  font-weight: 700;
  color: var(--text);
  background: rgba(37, 99, 235, 0.34);
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  line-height: 1.2;
  min-height: 38px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.22);
  transition: border-color 0.18s ease, background 0.18s ease, box-shadow 0.18s ease;
}

button:hover, .btn:hover {
  border-color: rgba(103, 232, 249, 0.64);
  background: rgba(37, 99, 235, 0.44);
  box-shadow: 0 14px 38px rgba(0, 0, 0, 0.30);
}

.btn.secondary {
  background: rgba(255, 255, 255, 0.06);
}

ul { margin: 8px 0; }
li { margin: 5px 0; }
.progress { font-size: 13px; color: var(--muted); margin-top: 8px; }

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  z-index: 1000;
  border: 1px solid rgba(103, 232, 249, 0.42);
  background: #06101d;
  color: var(--text);
  font-weight: 700;
  padding: 10px 14px;
  border-radius: 0 0 var(--radius) var(--radius);
  text-decoration: none;
}

.skip-link:focus,
.skip-link:focus-visible {
  left: 12px;
  top: 0;
}

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

a:not(.btn) {
  text-decoration: underline;
  text-underline-offset: 2px;
}

a.course-nav-link {
  text-decoration: none;
}

button:focus-visible,
.btn:focus-visible,
a:focus-visible,
input:focus-visible,
select:focus-visible,
audio:focus-visible {
  outline: 3px solid rgba(103, 232, 249, 0.86);
  outline-offset: 4px;
}

button:disabled,
.btn[aria-disabled="true"] {
  opacity: 0.65;
  cursor: not-allowed;
}

.narration-player-card {
  border-color: rgba(56, 189, 248, 0.30);
  background: rgba(255, 255, 255, 0.055);
}

.narration-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: flex-start;
  gap: 8px;
  margin: 10px 0;
}

.narration-controls .narration-nav {
  margin-top: 0;
  justify-content: flex-start;
}

.narration-controls .btn,
.narration-controls button {
  min-height: 38px;
  height: 38px;
  box-sizing: border-box;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  line-height: 1.2;
}

.narration-speed-label {
  font-size: 12px;
  color: var(--muted);
  margin-left: 4px;
  font-family: var(--font-mono);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.narration-speed {
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--bg-alt);
  color: var(--text);
  padding: 7px 9px;
  min-height: 38px;
}

.narration-audio {
  width: 100%;
  margin-top: 2px;
}

.narration-cc {
  margin-top: 10px;
  padding: 10px 12px;
  border-radius: var(--radius);
  border: 1px solid rgba(103, 232, 249, 0.22);
  background: var(--bg-alt);
  color: var(--muted-strong);
  font-family: var(--font-reading);
  line-height: 1.45;
}

.narration-cc.hidden {
  display: none;
}

.narration-card p {
  font-family: var(--font-reading);
  margin: 0 0 12px;
}

.narration-card p:last-child {
  margin-bottom: 0;
}

.code-example-card {
  display: grid;
  gap: 16px;
}

.code-example-intro,
.code-example-blurb {
  color: var(--muted-strong);
  font-family: var(--font-reading);
  margin: 0;
}

.code-example-list {
  display: grid;
  gap: 18px;
}

.code-example {
  display: grid;
  gap: 8px;
}

.code-example-title {
  margin: 0;
  color: var(--cyan);
  font-family: var(--font-ui);
  font-size: 1rem;
  letter-spacing: 0;
}

.code-figure {
  margin: 0;
}

.code-block {
  margin: 0;
  max-width: 100%;
  overflow: auto;
  border: 1px solid rgba(103, 232, 249, 0.28);
  border-radius: var(--radius);
  background: #030914;
  color: #e8f4ff;
  padding: 16px;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  line-height: 1.55;
  tab-size: 4;
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.035);
}

.code-block code {
  font-family: inherit;
}

.code-block:focus-visible {
  outline: 3px solid rgba(103, 232, 249, 0.86);
  outline-offset: 3px;
}

.tok-keyword { color: #67e8f9; }
.tok-register { color: #facc15; }
.tok-number { color: #86efac; }
.tok-label { color: #f0abfc; }
.tok-string { color: #fdba74; }
.tok-parameter { color: #93c5fd; }
.tok-comment { color: #9ca3af; font-style: italic; }

#quiz-result:focus {
  outline: none;
}

.quiz-form {
  display: grid;
  gap: 10px;
}

.quiz-question {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 10px;
  margin: 0;
  background: rgba(255, 255, 255, 0.035);
}

.quiz-question legend {
  color: var(--text);
  font-family: var(--font-ui);
  font-weight: 700;
  margin-bottom: 8px;
}

.quiz-question label {
  display: block;
  font-family: var(--font-reading);
  margin: 6px 0;
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}

@media (max-width: 980px) {
  .main-content.course-layout {
    display: block;
    padding: 16px;
  }

  .course-nav-pane {
    position: static;
    margin-bottom: 12px;
  }
}