/* ---------- Design tokens ---------- */

:root {
  color-scheme: light dark;
  --font: "Nunito", ui-rounded, "SF Pro Rounded", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;

  --bg: #f5f7fb;
  --surface: #ffffff;
  --surface-sunken: #eef1f6;
  --text: #182032;
  --text-muted: #4b5568;
  --border: #d8dee8;
  --border-strong: #aeb8c8;
  --focus: #1d4ed8;
  --success: #15803d;
  --success-soft: #dcfce7;
  --on-success: #ffffff;
  --danger: #b42318;
  --danger-soft: #fee4e2;
  --shadow: 0 1px 2px rgb(15 23 42 / 6%), 0 6px 20px rgb(15 23 42 / 6%);

  --radius-lg: 20px;
  --radius: 14px;
  --page-width: 1140px;

  /* Each structure has its own colour. The lesson page uses the blue one. */
  --accent: #2563eb;
  --accent-text: #1d4ed8;
  --accent-soft: #e3ecff;
  --on-accent: #ffffff;
}

.accent-linear {
  --accent: #2563eb;
  --accent-text: #1d4ed8;
  --accent-soft: #e3ecff;
}

.accent-cabang {
  --accent: #7c3aed;
  --accent-text: #6d28d9;
  --accent-soft: #efe7ff;
}

.accent-roda {
  --accent: #c2410c;
  --accent-text: #9a3412;
  --accent-soft: #ffeadb;
}

.accent-hierarki {
  --accent: #15803d;
  --accent-text: #166534;
  --accent-soft: #dcf5e4;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0e131d;
    --surface: #161d2a;
    --surface-sunken: #1f2838;
    --text: #e9eef6;
    --text-muted: #aab4c5;
    --border: #2c374a;
    --border-strong: #56647c;
    --focus: #9dbcff;
    --success: #4ade80;
    --success-soft: #12301f;
    --on-success: #0b1020;
    --danger: #fda29b;
    --danger-soft: #3a1714;
    --shadow: 0 1px 2px rgb(0 0 0 / 40%), 0 8px 24px rgb(0 0 0 / 30%);

    --accent: #7aa7ff;
    --accent-text: #a8c4ff;
    --accent-soft: #1b2a48;
    --on-accent: #0b1020;
  }

  .accent-linear {
    --accent: #7aa7ff;
    --accent-text: #a8c4ff;
    --accent-soft: #1b2a48;
  }

  .accent-cabang {
    --accent: #b197fc;
    --accent-text: #cbb8ff;
    --accent-soft: #2a2148;
  }

  .accent-roda {
    --accent: #fb9a5b;
    --accent-text: #ffbf94;
    --accent-soft: #3a2316;
  }

  .accent-hierarki {
    --accent: #5ad48a;
    --accent-text: #8be5ad;
    --accent-soft: #15301f;
  }
}

/* ---------- Shared pieces ---------- */

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 48px;
  padding: 10px 22px;
  border: 2px solid var(--accent);
  border-radius: 999px;
  background: var(--accent);
  color: var(--on-accent);
  font: inherit;
  font-weight: 800;
  text-decoration: none;
  cursor: pointer;
  transition: transform 0.12s ease, box-shadow 0.12s ease;
}

.button:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow);
}

.button--secondary {
  background: var(--surface);
  color: var(--accent-text);
}

.button:disabled {
  opacity: 0.4;
  cursor: default;
  transform: none;
  box-shadow: none;
}

.card {
  padding: 20px;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--surface);
  box-shadow: var(--shadow);
}

.card p {
  margin: 0 0 10px;
}

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

.card-title {
  margin: 0 0 12px;
  font-size: 1.15rem;
  font-weight: 800;
}

.hint {
  color: var(--text-muted);
  font-size: 0.95rem;
}

/* ---------- Lesson page ---------- */

.hero {
  border-bottom: 1px solid var(--border);
  background:
    radial-gradient(circle at 8% 18%, rgb(37 99 235 / 14%), transparent 38%),
    radial-gradient(circle at 92% 12%, rgb(124 58 237 / 14%), transparent 38%),
    radial-gradient(circle at 85% 95%, rgb(194 65 12 / 12%), transparent 38%),
    radial-gradient(circle at 15% 95%, rgb(21 128 61 / 12%), transparent 38%),
    var(--surface);
}

.hero-inner {
  max-width: var(--page-width);
  margin: 0 auto;
  padding: 56px 16px;
}

.hero-back {
  display: flex;
  width: fit-content;
  margin: 0 0 16px -8px;
}

.eyebrow {
  display: inline-block;
  margin: 0 0 16px;
  padding: 4px 14px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent-text);
  font-weight: 800;
  font-size: 0.9rem;
}

.hero-title {
  max-width: 18ch;
  margin: 0 0 16px;
  font-size: clamp(2rem, 6vw, 3.4rem);
  font-weight: 800;
  letter-spacing: -0.01em;
}

.hero-lead {
  max-width: 60ch;
  margin: 0 0 28px;
  font-size: 1.15rem;
  color: var(--text-muted);
}

.lesson-main {
  max-width: var(--page-width);
  margin: 0 auto;
  padding: 0 16px;
}

.section {
  margin: 56px 0;
}

.section-title {
  margin: 0 0 8px;
  font-size: clamp(1.5rem, 3.5vw, 2rem);
  font-weight: 800;
}

.section-lead {
  margin: 0 0 20px;
  color: var(--text-muted);
}

.section-title + .steps,
.section-title + .structure-grid,
.section-title + .table-card {
  margin-top: 20px;
}

.steps {
  display: grid;
  gap: 16px;
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: step;
}

.step {
  position: relative;
  padding: 20px 20px 20px 72px;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--surface);
  counter-increment: step;
}

.step::before {
  content: counter(step);
  position: absolute;
  top: 18px;
  left: 20px;
  display: grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent-text);
  font-weight: 800;
}

.structure-grid {
  display: grid;
  gap: 24px;
}

.structure-card {
  display: flex;
  flex-direction: column;
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--surface);
  box-shadow: var(--shadow);
}

.structure-card-diagram {
  height: 280px;
  padding: 16px;
  background: var(--accent-soft);
}

.structure-card-diagram .map {
  height: 100%;
}

.structure-card-diagram .map-node-label {
  stroke: var(--accent-soft);
}

.structure-card-body {
  display: flex;
  flex: 1;
  flex-direction: column;
  gap: 12px;
  padding: 20px 24px 24px;
}

.structure-card-body p {
  margin: 0;
}

.structure-card-body .button {
  align-self: flex-start;
  margin-top: auto;
}

.structure-card-title {
  margin: 0;
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--accent-text);
}

.definition {
  padding: 12px 14px;
  border-radius: var(--radius);
  background: var(--surface-sunken);
}

.definition-label {
  display: block;
  color: var(--accent-text);
  font-size: 0.8rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.example-banner {
  display: grid;
  place-items: center;
  height: 160px;
  margin: 0;
  background: var(--accent-soft);
  font-size: 4.5rem;
  line-height: 1;
}

.structure-card-body .table-structure {
  align-self: flex-start;
}

.structure-card-demo {
  color: var(--text-muted);
  font-weight: 700;
}

.table-card {
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--surface);
}

.comparison {
  width: 100%;
  border-collapse: collapse;
}

.comparison th,
.comparison td {
  padding: 14px 16px;
  border-bottom: 1px solid var(--border);
  text-align: left;
  vertical-align: top;
}

.comparison thead th {
  background: var(--surface-sunken);
  font-size: 0.9rem;
}

.comparison tbody tr:last-child > * {
  border-bottom: 0;
}

.table-structure {
  display: inline-block;
  padding: 2px 12px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent-text);
  font-weight: 800;
}

.quiz-score {
  display: inline-block;
  margin: 0 0 16px;
  padding: 6px 16px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent-text);
  font-weight: 700;
}

.quiz {
  display: grid;
  gap: 16px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.quiz-question {
  padding: 20px;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--surface);
}

.quiz-text {
  margin: 0 0 14px;
}

.quiz-number {
  display: block;
  color: var(--accent-text);
  font-weight: 800;
}

.quiz-options {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.quiz-options--count-3,
.quiz-options--list {
  grid-template-columns: minmax(0, 1fr);
}

.quiz-option {
  min-height: 48px;
  padding: 8px 12px;
  border: 2px solid var(--border-strong);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--text);
  font: inherit;
  font-weight: 800;
  cursor: pointer;
}

.quiz-options--list .quiz-option {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 10px 14px;
  text-align: left;
}

.quiz-letter {
  display: grid;
  flex: none;
  place-items: center;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--surface-sunken);
  font-size: 0.9rem;
}

.quiz-option:hover {
  border-color: var(--accent);
}

.quiz-option.is-correct {
  border-color: var(--success);
  background: var(--success-soft);
  color: var(--success);
}

.quiz-option.is-wrong {
  border-color: var(--danger);
  background: var(--danger-soft);
  color: var(--danger);
}

.quiz-option.is-correct::after {
  content: " ✓";
}

.quiz-option.is-wrong::after {
  content: " ✗";
}

.quiz-feedback {
  min-height: 1.6em;
  margin: 12px 0 0;
  font-weight: 700;
}

.quiz-feedback p {
  margin: 0;
}

.feedback-right {
  color: var(--success);
}

.feedback-wrong {
  color: var(--danger);
}

.lesson-footer {
  padding: 24px 16px 40px;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 0.95rem;
  text-align: center;
}

@media (min-width: 640px) {
  .quiz-options--count-3 {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .quiz-options--count-4 {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (min-width: 820px) {
  .steps {
    grid-template-columns: repeat(3, 1fr);
  }

  .structure-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .hero-inner {
    padding: 80px 16px;
  }
}

/* ---------- Demo pages: top bar ---------- */

.topbar {
  border-bottom: 1px solid var(--border);
  background: var(--surface);
}

.topbar-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 8px 16px;
  max-width: 1240px;
  margin: 0 auto;
  padding: 10px 16px;
}

.topbar-back {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  min-height: 44px;
  padding: 0 14px 0 8px;
  border-radius: 999px;
  color: var(--text);
  font-weight: 800;
  text-decoration: none;
}

.topbar-back:hover {
  background: var(--surface-sunken);
}

.structure-switch ul {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.switch-link {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: 0 14px;
  border: 2px solid var(--accent);
  border-radius: 999px;
  color: var(--accent-text);
  font-size: 0.95rem;
  font-weight: 800;
  text-decoration: none;
}

.switch-link:hover {
  background: var(--accent-soft);
}

.switch-link[aria-current] {
  background: var(--accent);
  color: var(--on-accent);
}

/* ---------- Demo pages: layout ---------- */

.demo {
  display: grid;
  grid-template-areas:
    "map"
    "site"
    "extra";
  gap: 20px;
  max-width: 1240px;
  margin: 0 auto;
  padding: 20px 16px 48px;
}

.demo > .browser-area {
  grid-area: site;
}

.demo > .map-card {
  grid-area: map;
}

.demo-extra {
  display: grid;
  grid-area: extra;
  align-content: start;
  gap: 20px;
}

@media (min-width: 1000px) {
  .demo {
    grid-template-areas:
      "site map"
      "site extra";
    grid-template-rows: auto 1fr;
    grid-template-columns: minmax(0, 1.35fr) minmax(360px, 1fr);
    align-items: start;
  }
}

.area-title {
  margin: 0 0 10px;
  color: var(--text-muted);
  font-size: 1rem;
  font-weight: 800;
}

/* ---------- Demo pages: the pretend browser and website ---------- */

.browser {
  overflow: hidden;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  background: var(--surface);
  box-shadow: var(--shadow);
}

.browser-bar {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 14px;
  border-bottom: 1px solid var(--border);
  background: var(--surface-sunken);
}

.browser-dots {
  display: flex;
  flex: none;
  gap: 6px;
}

.browser-dots span {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: #ff5f57;
}

.browser-dots span:nth-child(2) {
  background: #febc2e;
}

.browser-dots span:nth-child(3) {
  background: #28c840;
}

.browser-address {
  flex: 1;
  min-width: 0;
  margin: 0;
  padding: 4px 14px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--surface);
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: 0.9rem;
  overflow-wrap: anywhere;
}

.site {
  padding-bottom: 24px;
}

.site-header {
  padding: 14px 20px;
  border-bottom: 4px solid var(--accent);
  background: var(--accent-soft);
}

.site-name {
  margin: 0;
  color: var(--accent-text);
  font-size: 1.15rem;
  font-weight: 800;
}

.site-menu {
  margin-top: 12px;
  padding: 12px;
  border: 3px dashed var(--accent);
  border-radius: var(--radius);
}

.site-menu .site-links-title {
  margin-bottom: 8px;
}

.site-menu ul {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.menu-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  min-height: 44px;
  padding: 0 14px;
  border: 2px solid var(--accent);
  border-radius: 999px;
  background: var(--surface);
  color: var(--accent-text);
  font-weight: 800;
  text-decoration: none;
}

a.menu-link:hover {
  background: var(--accent);
  color: var(--on-accent);
}

.menu-link[aria-current] {
  background: var(--accent);
  color: var(--on-accent);
}

.site-page {
  padding: 28px 20px 4px;
  text-align: center;
}

.site-position {
  display: inline-block;
  margin: 0 0 8px;
  padding: 2px 12px;
  border-radius: 999px;
  background: var(--surface-sunken);
  color: var(--text-muted);
  font-size: 0.9rem;
  font-weight: 800;
}

.site-emoji {
  margin: 4px 0 8px;
  font-size: clamp(4rem, 14vw, 6rem);
  line-height: 1;
}

.site-title {
  margin: 0 0 8px;
  font-size: clamp(1.75rem, 5vw, 2.5rem);
  font-weight: 800;
}

.site-text {
  max-width: 52ch;
  margin: 0 auto;
  font-size: 1.1rem;
}

.site-links {
  margin: 24px 20px 0;
  padding: 16px;
  border: 3px dashed var(--accent);
  border-radius: var(--radius);
}

.site-links-title {
  margin: 0 0 12px;
  color: var(--accent-text);
  font-size: 0.85rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.pager {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.pager-end {
  display: grid;
  place-items: center;
  margin: 0;
  padding: 12px;
  border-radius: var(--radius);
  background: var(--surface-sunken);
  color: var(--text-muted);
  font-weight: 700;
  text-align: center;
}

.link-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 12px;
  margin: 0;
  padding: 0;
  list-style: none;
}

/* Space between link groups, for example "Naik", "Ke kiri / Ke kanan" and "Turun". */
.site-links > :not(.site-links-title) + * {
  margin-top: 12px;
}

/* A lone button (for example only "Ke kanan") uses the whole row, so its text never gets squeezed. */
.pager > .link-button:only-child {
  grid-column: 1 / -1;
}

/* On phones there is no room for two buttons side by side, so they stack. */
@media (max-width: 479px) {
  .pager {
    grid-template-columns: minmax(0, 1fr);
  }
}

.link-button {
  display: flex;
  align-items: center;
  gap: 12px;
  height: 100%;
  min-height: 64px;
  padding: 12px 16px;
  border-radius: var(--radius);
  background: var(--accent);
  color: var(--on-accent);
  font-weight: 800;
  text-decoration: none;
  box-shadow: 0 3px 0 rgb(0 0 0 / 18%);
  transition: transform 0.12s ease;
}

.link-button:hover {
  transform: translateY(-2px);
}

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

.link-button-icon {
  flex: none;
  font-size: 1.6rem;
  line-height: 1;
}

.link-button-text {
  display: flex;
  flex-direction: column;
  min-width: 0;
  line-height: 1.25;
}

.link-button-detail {
  font-size: 0.9rem;
  font-weight: 600;
}

.link-button--reverse {
  flex-direction: row-reverse;
  text-align: right;
}

.link-button--reverse .link-button-text {
  align-items: flex-end;
}

/* ---------- Demo pages: map ---------- */

.map {
  width: 100%;
  height: auto;
}

.map-card .map {
  max-height: 240px;
  margin: 0 auto;
}

@media (min-width: 1000px) {
  .map-card .map {
    max-height: 340px;
  }
}

.map-edge {
  stroke: var(--border-strong);
  stroke-width: 3;
  stroke-linecap: round;
}

.map-edge.is-active {
  stroke: var(--accent);
  stroke-width: 6;
}

.map-node-body {
  fill: var(--surface);
  stroke: var(--accent);
  stroke-width: 3;
}

.map--live .map-node-body {
  stroke: var(--border-strong);
}

.map--live .map-node.is-reachable .map-node-body {
  fill: var(--accent-soft);
  stroke: var(--accent);
  stroke-width: 4;
}

.map--live .map-node.is-current .map-node-body {
  fill: var(--accent);
  stroke: var(--accent);
}

.map-node-ring {
  display: none;
  fill: none;
  stroke: var(--accent);
  stroke-width: 4;
  transform-box: fill-box;
  transform-origin: center;
  animation: ring-pulse 1.6s ease-out infinite;
}

.map-node.is-current .map-node-ring {
  display: inline;
}

@keyframes ring-pulse {
  from {
    opacity: 0.8;
    transform: scale(1);
  }

  to {
    opacity: 0;
    transform: scale(1.6);
  }
}

.map-node-emoji {
  font-size: 24px;
  text-anchor: middle;
  dominant-baseline: central;
}

.map-node-label {
  fill: var(--text);
  font-family: var(--font);
  font-size: 16px;
  font-weight: 800;
  text-anchor: middle;
  paint-order: stroke;
  stroke: var(--surface);
  stroke-width: 5px;
  stroke-linejoin: round;
}

.map-node-check {
  display: none;
}

.map-node.is-visited:not(.is-current) .map-node-check {
  display: inline;
}

.map-node-check circle {
  fill: var(--success);
}

.map-node-check text {
  fill: var(--on-success);
  font-size: 13px;
  font-weight: 800;
  text-anchor: middle;
  dominant-baseline: central;
}

.map-status {
  display: grid;
  gap: 8px;
  margin: 16px 0 0;
}

.map-status div {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 2px 8px;
}

.map-status dt {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 800;
}

.map-status dd {
  margin: 0;
}

.legend-dot {
  display: inline-block;
  flex: none;
  width: 16px;
  height: 16px;
  border-radius: 50%;
}

.legend-dot--current {
  background: var(--accent);
}

.legend-dot--reachable {
  border: 3px solid var(--accent);
  background: var(--accent-soft);
}

/* ---------- Demo pages: trail and challenge ---------- */

.trail {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 0;
  margin: 0 0 12px;
  padding: 0;
  list-style: none;
}

.trail li {
  position: relative;
  padding: 2px 12px;
  border-radius: 999px;
  background: var(--surface-sunken);
  font-size: 0.95rem;
  font-weight: 700;
}

.trail li + li {
  margin-left: 26px;
}

.trail li + li::before {
  content: "→";
  content: "→" / "";
  position: absolute;
  left: -20px;
  color: var(--text-muted);
}

.trail li.is-current {
  background: var(--accent);
  color: var(--on-accent);
}

.trail-count {
  font-size: 1.05rem;
}

.answer summary {
  padding: 8px 0;
  color: var(--accent-text);
  font-weight: 800;
  cursor: pointer;
}

.answer[open] summary {
  margin-bottom: 8px;
}

.answer p {
  padding: 0 4px;
}

/* ---------- One-page version ---------- */

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.topic {
  padding: 48px 0;
  border-top: 1px solid var(--border);
  scroll-margin-top: 8px;
}

.topic:first-child {
  border-top: 0;
}

.topic-intro {
  display: grid;
  gap: 12px;
  max-width: 72ch;
}

.topic-intro p {
  margin: 0;
}

.topic-number {
  color: var(--accent-text);
  font-size: 0.9rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.topic-title {
  margin: 0;
  color: var(--accent-text);
  font-size: clamp(1.6rem, 4vw, 2.2rem);
  font-weight: 800;
}

.topic-demo {
  display: grid;
  gap: 20px;
  margin-top: 24px;
}

@media (min-width: 1000px) {
  .topic-demo {
    grid-template-columns: minmax(0, 1.35fr) minmax(320px, 1fr);
    align-items: start;
  }
}