:root {
  color-scheme: light;
  --course-accent: #8c1515;
  --course-accent-strong: #6b0f0f;
  --course-accent-soft: #f8eded;
  --course-bg: #fafaf7;
  --course-surface: #ffffff;
  --course-surface-muted: #f4f3ef;
  --course-ink: #1c1917;
  --course-muted: #6b6661;
  --course-faint: #918b85;
  --course-line: #e4e1dc;
  --course-code: #201f1d;
  --course-code-ink: #f4f2ec;
  --course-success: #18794e;
  --course-success-soft: #eaf6ef;
  --course-danger: #b42318;
  --course-danger-soft: #fff0ee;
  --course-warning-soft: #fff8e7;
  --course-radius: 14px;
  --course-sidebar: 288px;
  --course-shadow: 0 1px 2px rgb(50 42 35 / 0.04), 0 12px 32px rgb(50 42 35 / 0.035);
  font-family: "Avenir Next", Avenir, "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --course-accent: #e26d6d;
  --course-accent-strong: #f08a8a;
  --course-accent-soft: #341d1d;
  --course-bg: #171614;
  --course-surface: #211f1d;
  --course-surface-muted: #2a2825;
  --course-ink: #f3f0ea;
  --course-muted: #b9b2aa;
  --course-faint: #8f8982;
  --course-line: #3a3733;
  --course-code: #11110f;
  --course-code-ink: #f5f2eb;
  --course-success: #6fd19a;
  --course-success-soft: #173628;
  --course-danger: #ff8a80;
  --course-danger-soft: #3f211f;
  --course-warning-soft: #392f19;
  --course-shadow: 0 1px 2px rgb(0 0 0 / 0.2), 0 16px 42px rgb(0 0 0 / 0.12);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
    color-scheme: dark;
    --course-accent: #e26d6d;
    --course-accent-strong: #f08a8a;
    --course-accent-soft: #341d1d;
    --course-bg: #171614;
    --course-surface: #211f1d;
    --course-surface-muted: #2a2825;
    --course-ink: #f3f0ea;
    --course-muted: #b9b2aa;
    --course-faint: #8f8982;
    --course-line: #3a3733;
    --course-code: #11110f;
    --course-code-ink: #f5f2eb;
    --course-success: #6fd19a;
    --course-success-soft: #173628;
    --course-danger: #ff8a80;
    --course-danger-soft: #3f211f;
    --course-warning-soft: #392f19;
    --course-shadow: 0 1px 2px rgb(0 0 0 / 0.2), 0 16px 42px rgb(0 0 0 / 0.12);
  }
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  background: var(--course-bg);
}

body.course-enhanced {
  width: auto;
  max-width: none;
  min-height: 100dvh;
  margin: 0;
  padding: 0;
  background: var(--course-bg);
  color: var(--course-ink);
  font: 16px/1.75 "Avenir Next", Avenir, "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  -webkit-font-smoothing: antialiased;
}

.course-enhanced a {
  color: var(--course-accent);
  text-underline-offset: 3px;
}

.course-enhanced button,
.course-enhanced input,
.course-enhanced select {
  font: inherit;
}

.course-skip-link {
  position: fixed;
  top: 8px;
  left: 8px;
  z-index: 100;
  padding: 9px 13px;
  border-radius: 8px;
  background: var(--course-ink);
  color: var(--course-bg) !important;
  transform: translateY(-150%);
}

.course-skip-link:focus {
  transform: translateY(0);
}

.course-reading-progress {
  position: fixed;
  inset: 0 0 auto;
  z-index: 80;
  height: 3px;
  pointer-events: none;
}

.course-reading-progress::after {
  display: block;
  width: 100%;
  height: 100%;
  background: var(--course-accent);
  content: "";
  transform: scaleX(0);
  transform-origin: left;
  animation: course-reading-progress linear both;
  animation-timeline: scroll(root block);
}

@keyframes course-reading-progress {
  to { transform: scaleX(1); }
}

.course-app {
  display: grid;
  grid-template-columns: var(--course-sidebar) minmax(0, 1fr);
  min-height: 100dvh;
}

.course-sidebar {
  position: sticky;
  top: 0;
  z-index: 30;
  display: flex;
  flex-direction: column;
  width: var(--course-sidebar);
  height: 100dvh;
  border-right: 1px solid var(--course-line);
  background: color-mix(in srgb, var(--course-bg) 94%, transparent);
  backdrop-filter: blur(16px);
}

.course-sidebar-head {
  padding: 22px 20px 18px;
  border-bottom: 1px solid var(--course-line);
}

.course-brand {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  color: var(--course-muted) !important;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-decoration: none;
}

.course-brand-mark {
  display: grid;
  width: 25px;
  height: 25px;
  place-items: center;
  border-radius: 7px;
  background: var(--course-accent);
  color: #fff;
  font: 800 11px/1 ui-monospace, SFMono-Regular, Menlo, monospace;
}

.course-sidebar-code {
  margin: 19px 0 5px;
  color: var(--course-accent);
  font: 700 11px/1.4 ui-monospace, SFMono-Regular, Menlo, monospace;
  letter-spacing: 0.11em;
  text-transform: uppercase;
}

.course-sidebar-title {
  margin: 0;
  color: var(--course-ink);
  font-size: 19px;
  font-weight: 750;
  letter-spacing: -0.02em;
  line-height: 1.3;
}

.course-sidebar-subtitle {
  margin: 5px 0 0;
  color: var(--course-muted);
  font-size: 12px;
  line-height: 1.55;
}

.course-progress-card {
  margin-top: 17px;
  padding: 11px 12px;
  border: 1px solid var(--course-line);
  border-radius: 10px;
  background: var(--course-surface-muted);
}

.course-progress-copy {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  color: var(--course-muted);
  font-size: 11px;
}

.course-progress-copy strong {
  color: var(--course-ink);
}

.course-progress-track {
  height: 5px;
  margin-top: 8px;
  overflow: hidden;
  border-radius: 999px;
  background: var(--course-line);
}

.course-progress-value {
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: var(--course-accent);
  transition: width 240ms ease;
}

.course-sidebar-nav {
  flex: 1;
  min-height: 0;
  padding: 12px 10px 18px;
  overflow-y: auto;
  overscroll-behavior: contain;
}

.course-nav-label {
  margin: 12px 10px 6px;
  color: var(--course-faint);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.08em;
}

.course-nav-link {
  display: grid;
  grid-template-columns: 23px minmax(0, 1fr) auto;
  align-items: center;
  gap: 8px;
  width: 100%;
  min-height: 39px;
  margin: 2px 0;
  padding: 7px 9px;
  border: 0;
  border-radius: 9px;
  background: transparent;
  color: var(--course-muted) !important;
  font-size: 13px;
  text-align: left;
  text-decoration: none;
  cursor: pointer;
  transition: background 160ms ease, color 160ms ease, transform 120ms ease;
}

.course-nav-link:hover {
  background: var(--course-surface-muted);
  color: var(--course-ink) !important;
}

.course-nav-link:active {
  transform: translateY(1px);
}

.course-nav-link.is-active {
  background: var(--course-accent-soft);
  color: var(--course-accent) !important;
  font-weight: 700;
}

.course-nav-number {
  display: grid;
  width: 23px;
  height: 23px;
  place-items: center;
  border-radius: 7px;
  background: var(--course-surface-muted);
  color: var(--course-faint);
  font: 700 10px/1 ui-monospace, SFMono-Regular, Menlo, monospace;
}

.course-nav-link.is-active .course-nav-number {
  background: var(--course-accent);
  color: #fff;
}

.course-nav-text {
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.course-nav-status {
  color: var(--course-success);
  font-size: 11px;
  font-weight: 800;
  opacity: 0;
}

.course-nav-link.is-visited .course-nav-status {
  opacity: 1;
}

.course-sidebar-foot {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 11px 14px;
  border-top: 1px solid var(--course-line);
}

.course-sidebar-foot a,
.course-sidebar-foot button {
  border: 0;
  background: transparent;
  color: var(--course-muted) !important;
  font-size: 11px;
  text-decoration: none;
  cursor: pointer;
}

.course-sidebar-foot a:hover,
.course-sidebar-foot button:hover {
  color: var(--course-ink) !important;
}

.course-mobile-bar {
  display: none;
}

.course-content {
  min-width: 0;
}

.course-content > header,
.course-hero {
  max-width: none;
  margin: 0;
  padding: 58px clamp(24px, 6vw, 86px) 46px;
  border: 0;
  border-bottom: 1px solid var(--course-line);
  background: var(--course-surface);
  color: var(--course-ink);
  box-shadow: none;
}

.course-content > header > div,
.course-content > header > * {
  max-width: 920px;
}

.course-content > header .tag,
.course-content > header .label,
.course-content > header .eyebrow,
.course-hero-kicker {
  margin: 0 0 12px;
  color: var(--course-accent);
  font: 750 12px/1.5 ui-monospace, SFMono-Regular, Menlo, monospace;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.course-content > header h1,
.course-hero h1 {
  max-width: 880px;
  margin: 0;
  color: var(--course-ink);
  font: 760 clamp(35px, 5.2vw, 62px)/1.08 "Avenir Next", Avenir, "PingFang SC", sans-serif;
  letter-spacing: -0.045em;
}

.course-content > header p,
.course-hero-intro {
  max-width: 760px;
  margin: 18px 0 0;
  color: var(--course-muted);
  font-size: clamp(16px, 1.6vw, 19px);
  line-height: 1.75;
}

.course-hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 24px;
}

.course-hero-meta span {
  padding: 6px 10px;
  border: 1px solid var(--course-line);
  border-radius: 999px;
  background: var(--course-bg);
  color: var(--course-muted);
  font-size: 12px;
  font-weight: 650;
}

.course-content main,
.course-main {
  width: min(100%, 980px);
  max-width: none;
  margin: 0 auto;
  padding: 34px 34px 96px;
}

.course-content main > .intro,
.course-main > .intro {
  max-width: 760px;
  margin: 0 0 28px;
  color: var(--course-muted);
  font-size: 17px;
  line-height: 1.8;
}

.course-content nav:not(.course-sidebar-nav) {
  display: none;
}

.course-content .roadmap {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 8px;
  margin: 0 0 28px;
}

.course-content .roadmap div {
  padding: 14px 12px;
  border: 1px solid var(--course-line);
  border-radius: 10px;
  background: var(--course-surface);
  color: var(--course-ink);
  text-align: left;
}

.course-content .roadmap small {
  display: block;
  margin-bottom: 3px;
  color: var(--course-accent);
  font-size: 10px;
  font-weight: 700;
}

.course-chapter,
.course-content section.chapter,
.course-content main > section:not(.selected-detail) {
  max-width: none;
  margin: 12px 0;
  padding: 0;
  overflow: clip;
  border: 1px solid var(--course-line);
  border-radius: var(--course-radius);
  background: var(--course-surface);
  box-shadow: var(--course-shadow);
  scroll-margin-top: 18px;
}

.course-chapter-toggle {
  display: grid;
  grid-template-columns: 38px minmax(0, 1fr) 24px;
  align-items: start;
  gap: 13px;
  width: 100%;
  padding: 19px 20px;
  border: 0;
  background: transparent;
  color: var(--course-ink);
  text-align: left;
  cursor: pointer;
}

.course-chapter-toggle:hover {
  background: color-mix(in srgb, var(--course-surface-muted) 62%, transparent);
}

.course-chapter-toggle:active {
  transform: translateY(1px);
}

.course-chapter-index {
  display: grid;
  width: 34px;
  height: 34px;
  place-items: center;
  border-radius: 10px;
  background: var(--course-accent-soft);
  color: var(--course-accent);
  font: 800 11px/1 ui-monospace, SFMono-Regular, Menlo, monospace;
}

.course-chapter-heading {
  min-width: 0;
}

.course-chapter-heading strong {
  display: block;
  color: var(--course-ink);
  font-size: clamp(16px, 2vw, 20px);
  font-weight: 720;
  letter-spacing: -0.02em;
  line-height: 1.42;
}

.course-chapter-heading small {
  display: block;
  margin-top: 5px;
  color: var(--course-muted);
  font-size: 13px;
  font-weight: 500;
  line-height: 1.55;
}

.course-chapter-chevron {
  position: relative;
  width: 22px;
  height: 22px;
  margin-top: 5px;
}

.course-chapter-chevron::before,
.course-chapter-chevron::after {
  position: absolute;
  top: 10px;
  width: 8px;
  height: 1.5px;
  border-radius: 2px;
  background: var(--course-faint);
  content: "";
  transition: transform 180ms ease;
}

.course-chapter-chevron::before {
  left: 4px;
  transform: rotate(40deg);
}

.course-chapter-chevron::after {
  right: 4px;
  transform: rotate(-40deg);
}

.course-chapter.is-open .course-chapter-chevron::before {
  transform: rotate(-40deg);
}

.course-chapter.is-open .course-chapter-chevron::after {
  transform: rotate(40deg);
}

.course-chapter-body {
  padding: 4px 24px 28px 75px;
  border-top: 1px solid var(--course-line);
}

.course-chapter-body[hidden] {
  display: none;
}

.course-chapter-body > :first-child {
  margin-top: 22px;
}

.course-chapter-body > :last-child {
  margin-bottom: 0;
}

.course-chapter-body p,
.course-chapter-body li {
  color: var(--course-muted);
}

.course-chapter-body .lead {
  color: var(--course-ink);
  font-size: 17px;
  font-weight: 530;
  line-height: 1.8;
}

.course-chapter-body h3 {
  margin: 30px 0 10px;
  color: var(--course-ink);
  font-size: 18px;
  line-height: 1.4;
}

.course-chapter-body .analogy,
.course-chapter-body .rule,
.course-chapter-body .practice,
.course-chapter-body .pitfall {
  margin: 19px 0;
  padding: 16px 18px;
  border: 0;
  border-left: 3px solid var(--course-accent);
  border-radius: 0 10px 10px 0;
  background: var(--course-accent-soft);
  color: var(--course-muted);
}

.course-chapter-body .pitfall {
  border-left-color: var(--course-danger);
  background: var(--course-danger-soft);
}

.course-chapter-body .practice {
  border-left-color: var(--course-success);
  background: var(--course-success-soft);
}

.course-chapter-body .pitfall strong {
  color: var(--course-danger);
}

.course-chapter-body .practice strong {
  color: var(--course-success);
}

.course-content .diagram,
.course-content .layers {
  margin: 20px 0;
  padding: 18px;
  overflow-x: auto;
  border: 1px solid var(--course-line);
  border-radius: 11px;
  background: var(--course-surface-muted);
}

.course-content .diagram-title {
  margin-bottom: 13px;
  color: var(--course-faint);
  font: 700 11px/1.5 ui-monospace, SFMono-Regular, Menlo, monospace;
  letter-spacing: 0.08em;
}

.course-content .flow {
  display: flex;
  align-items: stretch;
  justify-content: center;
  gap: 7px;
  min-width: 650px;
}

.course-content .node,
.course-content .node.dark,
.course-content .node.warm {
  flex: 1;
  min-width: 105px;
  padding: 13px 9px;
  border: 1px solid var(--course-line);
  border-radius: 9px;
  background: var(--course-surface);
  color: var(--course-ink);
  text-align: center;
}

.course-content .node.dark {
  border-color: var(--course-accent);
  background: var(--course-accent);
  color: #fff;
}

.course-content .node.warm {
  background: var(--course-warning-soft);
}

.course-content .node small,
.course-content .node.dark small {
  display: block;
  color: inherit;
  font-size: 11px;
  opacity: 0.72;
}

.course-content .arrow {
  align-self: center;
  color: var(--course-faint);
}

.course-content .stack {
  display: grid;
  gap: 7px;
  min-width: 560px;
}

.course-content .stack .row {
  display: grid;
  grid-template-columns: 150px 1fr;
  gap: 7px;
}

.course-content .stack .row b,
.course-content .stack .row span,
.course-content .layers div {
  padding: 12px 14px;
  border: 0;
  border-radius: 8px;
  background: var(--course-surface);
  color: var(--course-muted);
  box-shadow: none;
}

.course-content .stack .row b {
  background: var(--course-accent);
  color: #fff;
}

.course-content table {
  display: table;
  width: 100%;
  margin: 20px 0;
  overflow: hidden;
  border: 1px solid var(--course-line);
  border-collapse: separate;
  border-spacing: 0;
  border-radius: 10px;
  background: var(--course-surface);
}

.course-content th,
.course-content td {
  padding: 11px 13px;
  border: 0;
  border-bottom: 1px solid var(--course-line);
  color: var(--course-muted);
  text-align: left;
}

.course-content tr:last-child td {
  border-bottom: 0;
}

.course-content th {
  background: var(--course-surface-muted);
  color: var(--course-ink);
  font-size: 13px;
}

.course-code-wrap {
  position: relative;
  margin: 20px 0;
}

.course-code-wrap pre,
.course-content pre {
  margin: 0;
  padding: 21px;
  overflow: auto;
  border: 1px solid color-mix(in srgb, var(--course-code) 85%, white);
  border-radius: 11px;
  background: var(--course-code);
  color: var(--course-code-ink);
  font: 13px/1.65 ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  box-shadow: none;
}

.course-content code {
  padding: 0.12em 0.35em;
  border-radius: 5px;
  background: var(--course-surface-muted);
  color: var(--course-accent-strong);
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  font-size: 0.9em;
}

.course-code-wrap pre code {
  padding: 0;
  background: transparent;
  color: inherit;
}

.course-copy-button {
  position: absolute;
  top: 9px;
  right: 9px;
  z-index: 2;
  padding: 5px 9px;
  border: 1px solid rgb(255 255 255 / 0.17);
  border-radius: 7px;
  background: rgb(255 255 255 / 0.08);
  color: #eeece6;
  font-size: 11px;
  cursor: pointer;
}

.course-copy-button:hover {
  background: rgb(255 255 255 / 0.15);
}

.course-content .checkpoint {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
}

.course-content .checkpoint span,
.course-content .summary {
  border: 1px solid var(--course-line);
  background: var(--course-surface);
  color: var(--course-muted);
}

.course-content .checkpoint span {
  padding: 6px 10px;
  border-radius: 999px;
  font-size: 12px;
}

.course-content .summary {
  margin-top: 28px;
  padding: 26px;
  border-radius: var(--course-radius);
}

.course-content .summary h2 {
  margin-top: 0;
  color: var(--course-ink);
}

.course-quiz-main {
  width: min(100%, 900px);
}

.course-quiz-main > h1,
.course-quiz-main > .intro,
.course-quiz-main > .progress {
  display: none;
}

.course-quiz-main form {
  margin: 0;
}

.course-quiz-main fieldset {
  margin: 0 0 13px;
  padding: 20px;
  border: 1px solid var(--course-line);
  border-radius: var(--course-radius);
  background: var(--course-surface);
  box-shadow: var(--course-shadow);
  scroll-margin-top: 20px;
}

.course-quiz-main fieldset.correct {
  border-color: color-mix(in srgb, var(--course-success) 44%, var(--course-line));
  background: var(--course-success-soft);
}

.course-quiz-main fieldset.incorrect {
  border-color: color-mix(in srgb, var(--course-danger) 42%, var(--course-line));
  background: var(--course-danger-soft);
}

.course-quiz-main legend {
  max-width: 100%;
  padding: 0 6px;
  color: var(--course-ink);
  font-size: 16px;
  font-weight: 720;
  line-height: 1.55;
}

.course-quiz-main fieldset label,
.course-quiz-main .form-check {
  display: flex;
  align-items: flex-start;
  gap: 9px;
  margin: 7px 0;
  padding: 10px 11px;
  border: 1px solid transparent;
  border-radius: 9px;
  color: var(--course-muted);
  cursor: pointer;
}

.course-quiz-main fieldset label:hover {
  border-color: var(--course-line);
  background: var(--course-surface-muted);
}

.course-quiz-main input[type="radio"] {
  width: 17px;
  height: 17px;
  margin: 3px 0 0;
  accent-color: var(--course-accent);
}

.course-quiz-main fieldset p,
.course-quiz-main .explain {
  margin: 13px 0 0;
  padding: 12px 14px;
  border: 0;
  border-left: 3px solid var(--course-accent);
  border-radius: 0 8px 8px 0;
  background: var(--course-accent-soft);
  color: var(--course-muted);
  font-size: 14px;
}

.course-quiz-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-top: 20px;
}

.course-quiz-main button[type="submit"],
.course-primary-action {
  min-height: 44px;
  padding: 10px 18px;
  border: 1px solid var(--course-accent-strong);
  border-radius: 10px;
  background: var(--course-accent);
  color: #fff;
  font-weight: 750;
  cursor: pointer;
}

.course-quiz-main button[type="submit"]:hover,
.course-primary-action:hover {
  background: var(--course-accent-strong);
}

.course-quiz-main button[type="submit"]:active,
.course-primary-action:active {
  transform: translateY(1px);
}

.course-secondary-action {
  min-height: 44px;
  padding: 10px 16px;
  border: 1px solid var(--course-line);
  border-radius: 10px;
  background: var(--course-surface);
  color: var(--course-ink);
  font-weight: 700;
  cursor: pointer;
}

.course-result,
.course-quiz-main .result {
  min-height: 30px;
  margin: 18px 0;
  color: var(--course-ink);
  font-size: 20px;
  font-weight: 750;
}

.course-quiz-main > p:last-child {
  display: none;
}

.course-interactive-main {
  width: min(100%, 1100px) !important;
}

.course-interactive-main #attention-evolution-tutorial {
  color: var(--course-ink);
}

.course-interactive-main .viz-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: end;
  gap: 9px;
  margin-bottom: 16px;
}

.course-interactive-main .form-label {
  display: grid;
  gap: 5px;
  color: var(--course-muted);
  font-size: 12px;
}

.course-interactive-main .form-select,
.course-interactive-main .btn,
.course-interactive-main .viz-badge {
  min-height: 38px;
  padding: 8px 11px;
  border: 1px solid var(--course-line);
  border-radius: 9px;
  background: var(--course-surface);
  color: var(--course-ink);
}

.course-interactive-main .btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  cursor: pointer;
}

.course-interactive-main .btn:hover,
.course-interactive-main .btn[aria-pressed="true"],
.course-interactive-main .btn.is-selected {
  border-color: color-mix(in srgb, var(--course-accent) 45%, var(--course-line));
  background: var(--course-accent-soft);
  color: var(--course-accent);
}

.course-interactive-main .viz-badge {
  color: var(--course-muted);
  font-size: 12px;
}

.course-interactive-main .card {
  padding: 22px;
  border: 1px solid var(--course-line);
  border-radius: var(--course-radius);
  background: var(--course-surface);
  box-shadow: var(--course-shadow);
}

.course-interactive-main .detail-block h3,
.course-interactive-main .detail-heading h2 {
  color: var(--course-ink);
}

.course-interactive-main .detail-block,
.course-interactive-main .formula,
.course-interactive-main .comparison-side,
.course-interactive-main .source-strip {
  color: var(--course-muted);
}

.course-interactive-main .formula {
  border-color: var(--course-line) !important;
}

.course-interactive-main .formula code {
  color: var(--course-accent-strong);
}

.course-interactive-main .tree-edge {
  stroke: var(--course-faint) !important;
}

.course-interactive-main .lane-label,
.course-interactive-main .edge-label {
  fill: var(--course-muted) !important;
}

.course-interactive-main .quiz-options label {
  color: var(--course-muted);
}

.course-interactive-main progress {
  accent-color: var(--course-accent);
}

.course-empty-state {
  padding: 28px;
  border: 1px dashed var(--course-line);
  border-radius: var(--course-radius);
  color: var(--course-muted);
  text-align: center;
}

.course-toast {
  position: fixed;
  right: 20px;
  bottom: 20px;
  z-index: 90;
  max-width: min(360px, calc(100vw - 40px));
  padding: 10px 13px;
  border: 1px solid var(--course-line);
  border-radius: 9px;
  background: var(--course-ink);
  color: var(--course-bg);
  font-size: 13px;
  box-shadow: var(--course-shadow);
}

.course-sidebar-scrim {
  display: none;
}

@media (max-width: 1050px) {
  .course-app {
    display: block;
    padding-top: 55px;
  }

  .course-mobile-bar {
    position: fixed;
    inset: 0 0 auto;
    z-index: 60;
    display: grid;
    grid-template-columns: auto minmax(0, 1fr) auto;
    align-items: center;
    gap: 10px;
    height: 55px;
    padding: 0 12px;
    border-bottom: 1px solid var(--course-line);
    background: color-mix(in srgb, var(--course-bg) 92%, transparent);
    backdrop-filter: blur(16px);
  }

  .course-mobile-bar button {
    min-height: 36px;
    padding: 7px 10px;
    border: 1px solid var(--course-line);
    border-radius: 9px;
    background: var(--course-surface);
    color: var(--course-ink);
    font-size: 12px;
    font-weight: 700;
    cursor: pointer;
  }

  .course-mobile-title {
    min-width: 0;
    overflow: hidden;
    color: var(--course-ink);
    font-size: 13px;
    font-weight: 700;
    text-overflow: ellipsis;
    white-space: nowrap;
  }

  .course-mobile-progress {
    color: var(--course-muted);
    font: 700 11px/1 ui-monospace, SFMono-Regular, Menlo, monospace;
  }

  .course-sidebar {
    position: fixed;
    inset: 0 auto 0 0;
    z-index: 70;
    width: min(88vw, var(--course-sidebar));
    transform: translateX(-105%);
    transition: transform 220ms cubic-bezier(0.16, 1, 0.3, 1);
  }

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

  .course-sidebar-scrim {
    position: fixed;
    inset: 0;
    z-index: 65;
    display: block;
    border: 0;
    background: rgb(20 18 16 / 0.38);
    opacity: 0;
    pointer-events: none;
    transition: opacity 180ms ease;
  }

  .course-sidebar-scrim.is-open {
    opacity: 1;
    pointer-events: auto;
  }

  body.course-nav-open {
    overflow: hidden;
  }

  .course-content > header,
  .course-hero {
    padding-top: 45px;
  }
}

@media (max-width: 720px) {
  .course-content > header,
  .course-hero {
    padding: 34px 20px 31px;
  }

  .course-content > header h1,
  .course-hero h1 {
    font-size: clamp(32px, 10vw, 44px);
    letter-spacing: -0.04em;
  }

  .course-content > header p,
  .course-hero-intro {
    margin-top: 14px;
    font-size: 16px;
  }

  .course-content main,
  .course-main {
    width: 100%;
    padding: 24px 14px 72px;
  }

  .course-content .roadmap {
    grid-template-columns: 1fr 1fr;
  }

  .course-chapter-toggle {
    grid-template-columns: 32px minmax(0, 1fr) 20px;
    gap: 10px;
    padding: 16px 14px;
  }

  .course-chapter-index {
    width: 30px;
    height: 30px;
    border-radius: 8px;
  }

  .course-chapter-body {
    padding: 1px 16px 22px;
  }

  .course-content table {
    display: block;
    overflow-x: auto;
    white-space: nowrap;
  }

  .course-content .stack .row {
    grid-template-columns: 105px 1fr;
  }

  .course-quiz-main fieldset {
    padding: 16px 13px;
  }

  .course-interactive-main .card {
    padding: 16px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}

@media print {
  .course-sidebar,
  .course-mobile-bar,
  .course-sidebar-scrim,
  .course-reading-progress,
  .course-copy-button {
    display: none !important;
  }

  .course-app {
    display: block;
  }

  .course-app,
  .course-content,
  .course-chapter-body {
    padding: 0;
  }

  .course-chapter-body[hidden] {
    display: block;
  }

  .course-chapter-toggle {
    border-bottom: 1px solid var(--course-line);
  }
}