:root {
  color-scheme: light;
  --ink: #17201a;
  --muted: #5d675f;
  --paper: #fbfaf4;
  --surface: #ffffff;
  --line: #d8d8cf;
  --leaf: #245d3d;
  --leaf-2: #3e7a53;
  --wine: #7b2337;
  --gold: #c99039;
  --mist: #edf2ea;
  --sky: #d9e7ee;
  --danger: #a83232;
  --ok: #257049;
  --shadow: 0 18px 45px rgba(32, 38, 31, 0.12);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  overflow-x: hidden;
  background: var(--paper);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.5;
}

button,
input {
  font: inherit;
}

button {
  cursor: pointer;
}

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

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  width: 100%;
  max-width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  min-height: 72px;
  padding: 12px clamp(16px, 4vw, 42px);
  border-bottom: 1px solid rgba(36, 93, 61, 0.18);
  background: rgba(251, 250, 244, 0.92);
  backdrop-filter: blur(16px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  color: var(--ink);
  text-decoration: none;
  min-width: 190px;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  border: 2px solid var(--leaf);
  border-radius: 8px;
  color: var(--leaf);
  font-weight: 800;
}

.brand small {
  display: block;
  color: var(--muted);
  font-size: 0.78rem;
}

.tabs,
.segmented,
.hero-actions,
.topic-filters,
.question-actions {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  min-width: 0;
}

.tab,
.segment,
.primary-action,
.secondary-action,
.icon-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 42px;
  min-width: 0;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--ink);
  padding: 0 14px;
  text-decoration: none;
  transition: transform 140ms ease, border-color 140ms ease, background 140ms ease, color 140ms ease;
}

.tab svg,
.segment svg,
.primary-action svg,
.secondary-action svg,
.icon-button svg,
.search-box svg {
  width: 18px;
  height: 18px;
  flex: 0 0 auto;
}

.tab:hover,
.segment:hover,
.primary-action:hover,
.secondary-action:hover,
.icon-button:hover,
.module-link:hover {
  transform: translateY(-1px);
}

.tab.is-active,
.segment.is-active,
.primary-action {
  border-color: var(--leaf);
  background: var(--leaf);
  color: #fff;
}

.secondary-action {
  background: #fffdf7;
}

.hero-band {
  position: relative;
  min-height: min(580px, calc(100vh - 64px));
  display: grid;
  align-items: end;
  gap: 28px;
  padding: clamp(36px, 7vw, 76px) clamp(18px, 5vw, 70px);
  background:
    linear-gradient(90deg, rgba(18, 31, 22, 0.86), rgba(18, 31, 22, 0.47), rgba(18, 31, 22, 0.18)),
    url("https://images.unsplash.com/photo-1506377247377-2a5b3b417ebb?auto=format&fit=crop&w=1800&q=82") center/cover;
  color: #fff;
}

.hero-band > * {
  min-width: 0;
}

.hero-content {
  width: 100%;
  max-width: 760px;
  min-width: 0;
}

.eyebrow {
  margin: 0 0 10px;
  color: var(--gold);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

.hero-band .eyebrow {
  color: #f1c77c;
}

h1,
h2,
h3 {
  letter-spacing: 0;
  line-height: 1.08;
}

h1 {
  margin: 0;
  max-width: min(720px, 100%);
  font-size: clamp(2.4rem, 8vw, 5.9rem);
  overflow-wrap: break-word;
}

h2 {
  margin: 0;
  font-size: clamp(1.7rem, 4vw, 3rem);
}

h3 {
  margin: 0 0 12px;
  font-size: clamp(1.18rem, 2vw, 1.55rem);
}

.hero-copy {
  max-width: min(620px, 100%);
  margin: 18px 0 24px;
  color: rgba(255, 255, 255, 0.9);
  font-size: clamp(1rem, 2vw, 1.24rem);
}

.exam-strip {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1px;
  width: min(760px, 100%);
  max-width: 760px;
  border: 1px solid rgba(255, 255, 255, 0.35);
  background: rgba(255, 255, 255, 0.2);
  backdrop-filter: blur(12px);
}

.exam-strip div {
  padding: 18px;
  background: rgba(255, 255, 255, 0.13);
}

.exam-strip strong,
.exam-strip span {
  display: block;
}

.exam-strip strong {
  font-size: clamp(1.45rem, 4vw, 2.35rem);
}

.exam-strip span {
  color: rgba(255, 255, 255, 0.86);
}

main > .view {
  display: none;
  padding: clamp(32px, 5vw, 56px) clamp(16px, 5vw, 70px);
}

main > .view.is-visible {
  display: block;
}

.section-head {
  display: flex;
  justify-content: space-between;
  align-items: end;
  gap: 18px;
  margin-bottom: 24px;
}

.search-box {
  display: flex;
  align-items: center;
  gap: 10px;
  width: min(420px, 100%);
  min-height: 46px;
  padding: 0 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--muted);
}

.search-box input {
  width: 100%;
  border: 0;
  outline: 0;
  color: var(--ink);
  background: transparent;
}

.guide-layout {
  display: grid;
  grid-template-columns: minmax(220px, 300px) minmax(0, 1fr);
  gap: clamp(20px, 4vw, 40px);
  align-items: start;
}

.module-nav {
  position: sticky;
  top: 92px;
  display: grid;
  gap: 8px;
}

.module-link {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 10px;
  width: 100%;
  min-height: 54px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--ink);
  text-align: left;
}

.module-link.is-active {
  border-color: var(--leaf);
  background: var(--mist);
}

.module-number {
  display: grid;
  place-items: center;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: var(--sky);
  color: var(--ink);
  font-weight: 800;
}

.module-link.is-active .module-number {
  background: var(--leaf);
  color: #fff;
}

.module-count {
  color: var(--muted);
  font-size: 0.82rem;
}

.module-content {
  display: grid;
  gap: 22px;
}

.study-block,
.quick-block,
.source-card,
.flashcard,
.question-panel,
.quiz-controls,
.score-summary {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.study-block {
  padding: clamp(20px, 3vw, 30px);
}

.study-block h3 {
  display: flex;
  align-items: center;
  gap: 10px;
}

.study-block h3 svg {
  width: 22px;
  height: 22px;
  color: var(--leaf);
}

.study-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 14px;
}

.fact-list {
  display: grid;
  gap: 10px;
  padding: 0;
  margin: 0;
  list-style: none;
}

.fact-list li {
  display: grid;
  grid-template-columns: 10px 1fr;
  gap: 10px;
}

.fact-list li::before {
  content: "";
  width: 7px;
  height: 7px;
  margin-top: 9px;
  border-radius: 50%;
  background: var(--gold);
}

.quick-block {
  padding: 18px;
  background: #fffdf7;
}

.quick-block strong {
  color: var(--wine);
}

.tag-row,
.mini-tags {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-top: 16px;
}

.tag {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  border: 1px solid rgba(36, 93, 61, 0.18);
  border-radius: 999px;
  padding: 0 10px;
  background: var(--mist);
  color: var(--leaf);
  font-size: 0.82rem;
  font-weight: 700;
}

.quiz-controls {
  display: grid;
  grid-template-columns: minmax(210px, auto) minmax(210px, 1fr) minmax(260px, 2fr) auto;
  gap: 16px;
  align-items: end;
  padding: 18px;
  margin-bottom: 22px;
}

.control-group {
  display: grid;
  gap: 8px;
}

.control-label {
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0;
}

.count-control {
  grid-template-columns: 1fr auto;
  align-items: center;
}

.count-control .control-label {
  grid-column: 1 / -1;
}

input[type="range"] {
  width: 100%;
  accent-color: var(--leaf);
}

output {
  min-width: 34px;
  text-align: right;
  font-weight: 800;
}

.topic-check {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 34px;
  padding: 0 10px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: #fffdf7;
  font-size: 0.88rem;
  white-space: nowrap;
}

.topic-check input {
  width: 16px;
  height: 16px;
  accent-color: var(--leaf);
}

.score-pill {
  display: inline-flex;
  align-items: center;
  min-height: 36px;
  padding: 0 12px;
  border: 1px solid rgba(123, 35, 55, 0.18);
  border-radius: 999px;
  background: #fff4f1;
  color: var(--wine);
  font-weight: 800;
}

.quiz-shell {
  display: grid;
  gap: 16px;
}

.quiz-progress {
  display: grid;
  gap: 8px;
  color: var(--muted);
  font-weight: 800;
}

.progress-track {
  height: 10px;
  border-radius: 999px;
  background: #e4e5da;
  overflow: hidden;
}

#progress-bar {
  display: block;
  height: 100%;
  width: 0;
  background: var(--leaf);
  transition: width 200ms ease;
}

.question-panel {
  padding: clamp(20px, 4vw, 34px);
}

.question-meta {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 14px;
}

.question-panel h3 {
  font-size: clamp(1.24rem, 2.5vw, 1.8rem);
}

.options-grid {
  display: grid;
  gap: 10px;
  margin: 20px 0;
}

.option-button {
  min-height: 58px;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fffdf7;
  color: var(--ink);
  text-align: left;
}

.option-button:hover {
  border-color: var(--leaf);
}

.option-button.is-correct {
  border-color: var(--ok);
  background: #eaf5ee;
}

.option-button.is-wrong {
  border-color: var(--danger);
  background: #fff0ef;
}

.option-button.is-selected {
  border-color: var(--leaf);
  background: var(--mist);
}

.feedback {
  display: none;
  padding: 14px 16px;
  border-left: 4px solid var(--gold);
  background: #fff8e8;
}

.feedback.is-visible {
  display: block;
}

.feedback strong {
  display: block;
  margin-bottom: 4px;
}

.question-actions {
  justify-content: space-between;
  margin-top: 20px;
}

.question-source {
  color: var(--muted);
  font-size: 0.92rem;
}

.score-summary {
  display: grid;
  gap: 16px;
  padding: clamp(22px, 4vw, 34px);
}

.score-summary strong {
  color: var(--leaf);
}

.review-list {
  display: grid;
  gap: 12px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.review-list li {
  border-top: 1px solid var(--line);
  padding-top: 12px;
}

.flashcard-board {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 16px;
}

.flashcard {
  min-height: 230px;
  padding: 22px;
  display: grid;
  align-content: space-between;
  gap: 20px;
  transition: transform 180ms ease;
}

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

.flashcard p {
  margin: 0;
}

.flashcard .answer {
  display: none;
  color: var(--muted);
}

.flashcard.is-open .answer {
  display: block;
}

.source-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 16px;
}

.source-card {
  display: grid;
  gap: 10px;
  padding: 18px;
}

.source-card a {
  font-weight: 800;
}

.source-card p {
  margin: 0;
  color: var(--muted);
}

.site-footer {
  padding: 28px clamp(16px, 5vw, 70px);
  border-top: 1px solid var(--line);
  color: var(--muted);
  background: #fffdf7;
}

.hidden {
  display: none !important;
}

@media (max-width: 1050px) {
  .quiz-controls {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 820px) {
  .topbar {
    align-items: stretch;
    flex-direction: column;
  }

  .brand {
    min-width: 0;
  }

  .tabs {
    width: 100%;
    max-width: 100%;
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .topbar .tabs {
    width: calc(100vw - 32px);
  }

  .tab {
    padding: 0 8px;
    width: 100%;
  }

  .tab span {
    font-size: 0.86rem;
    max-width: 100%;
    overflow: hidden;
    text-overflow: ellipsis;
  }

  .hero-band {
    min-height: auto;
    padding-top: 54px;
    overflow: hidden;
  }

  .exam-strip,
  .guide-layout,
  .quiz-controls {
    grid-template-columns: 1fr;
  }

  .module-nav {
    position: static;
    grid-template-columns: 1fr;
  }

  .section-head {
    align-items: stretch;
    flex-direction: column;
  }
}

@media (max-width: 520px) {
  .hero-actions,
  .question-actions,
  .segmented {
    align-items: stretch;
    flex-direction: column;
  }

  .primary-action,
  .secondary-action,
  .segment {
    width: 100%;
  }

  .tabs {
    gap: 6px;
  }

  .topbar .tabs {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .hero-band {
    padding: 32px 24px 26px;
  }

  .exam-strip div {
    padding: 12px 18px;
  }

  main > .view {
    padding-top: 24px;
  }

  .tab {
    min-height: 48px;
    flex-direction: column;
    gap: 2px;
  }

  .tab svg {
    width: 17px;
    height: 17px;
  }

  .tab span {
    font-size: 0.78rem;
  }

  h1 {
    font-size: clamp(2rem, 9vw, 2.35rem);
    line-height: 1.12;
    max-width: 100%;
  }

  .hero-content {
    max-width: 340px;
  }

  .hero-copy,
  .exam-strip {
    max-width: 340px;
  }
}