:root {
  color-scheme: light;
  --bg: #f6f2ea;
  --surface: #fffdf8;
  --surface-strong: #f0eadf;
  --ink: #1f2522;
  --muted: #647067;
  --line: #d9d0c1;
  --accent: #21706a;
  --accent-strong: #154f4d;
  --gold: #a87422;
  --bad: #a33a32;
  --good: #207044;
  --shadow: 0 18px 42px rgba(39, 34, 27, 0.12);
  font-family: "Source Sans 3", "Segoe UI", system-ui, sans-serif;
}

* {
  box-sizing: border-box;
}

html,
body {
  min-height: 100%;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
}

button,
a {
  -webkit-tap-highlight-color: transparent;
}

button {
  font: inherit;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 5;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  min-height: 60px;
  padding: 0.8rem clamp(1rem, 3vw, 2rem);
  border-bottom: 1px solid var(--line);
  background: rgba(246, 242, 234, 0.94);
  backdrop-filter: blur(12px);
}

.back-link {
  color: var(--accent-strong);
  font-weight: 800;
  text-decoration: none;
}

.topbar-status {
  color: var(--muted);
  font-size: 0.92rem;
}

.study-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1rem;
  width: min(1120px, 100%);
  margin: 0 auto;
  padding: clamp(1rem, 3vw, 2rem);
}

.control-panel,
.quiz-panel,
.review-panel {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.control-panel,
.review-panel {
  align-self: start;
  display: grid;
  gap: 1rem;
  padding: 1rem;
}

.control-panel {
  grid-template-columns: minmax(220px, 1fr) minmax(280px, 420px) minmax(170px, 220px) minmax(170px, 220px);
  align-items: start;
}

.quiz-panel {
  padding: clamp(1.1rem, 3vw, 2rem);
}

.eyebrow,
.source-label,
.progress-label,
.answer-label {
  margin: 0 0 0.35rem;
  color: var(--gold);
  font-size: 0.76rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1,
h2,
p {
  margin-top: 0;
}

h1 {
  margin-bottom: 0.55rem;
  font-size: clamp(1.45rem, 3vw, 2.15rem);
  line-height: 1.05;
}

.deck-summary {
  margin-bottom: 0;
  color: var(--muted);
}

.mode-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.5rem;
}

.mode-button,
.secondary-button,
.primary-button,
.success-button,
.review-button,
.choice-button {
  min-height: 44px;
  border-radius: 8px;
  border: 1px solid var(--line);
  cursor: pointer;
}

.mode-button,
.secondary-button {
  background: var(--surface-strong);
  color: var(--ink);
  font-weight: 700;
}

.mode-button.active,
.primary-button {
  border-color: var(--accent);
  background: var(--accent);
  color: white;
}

.success-button {
  border-color: rgba(32, 112, 68, 0.36);
  background: #dff1e7;
  color: var(--good);
  font-weight: 800;
}

.review-button {
  border-color: rgba(163, 58, 50, 0.35);
  background: #f7e3df;
  color: var(--bad);
  font-weight: 800;
}

.control-row,
.action-row,
.self-grade {
  display: flex;
  gap: 0.65rem;
  flex-wrap: wrap;
}

.control-row > *,
.action-row > * {
  flex: 1 1 120px;
}

.progress-card {
  display: grid;
  gap: 0.45rem;
  padding: 0.9rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #faf6ee;
}

.progress-card strong {
  font-size: 1.35rem;
}

.meter {
  overflow: hidden;
  height: 8px;
  border-radius: 999px;
  background: #e7ded0;
}

.meter span {
  display: block;
  width: 0;
  height: 100%;
  background: var(--accent);
  transition: width 180ms ease;
}

.list-header {
  display: flex;
  justify-content: space-between;
  align-items: start;
  gap: 1rem;
  margin-bottom: 1.4rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--line);
}

.list-header h2 {
  margin-bottom: 0;
  font-size: clamp(1.35rem, 2.5vw, 2rem);
}

#visibleCount {
  color: var(--muted);
  font-size: 0.92rem;
  font-weight: 700;
  white-space: nowrap;
}

.question-list {
  display: grid;
  gap: 1rem;
}

.question-card {
  scroll-margin-top: 78px;
  padding: clamp(1rem, 2.2vw, 1.35rem);
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fffaf1;
}

.question-meta {
  display: flex;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 0.85rem;
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0;
}

.question-card h3 {
  margin: 0 0 1rem;
  font-size: clamp(1.08rem, 2vw, 1.42rem);
  line-height: 1.28;
  letter-spacing: 0;
}

.question-body {
  display: grid;
  gap: 0.9rem;
}

.choice-list {
  display: grid;
  gap: 0.72rem;
  margin: 1rem 0 1.2rem;
}

.matching-list {
  display: grid;
  gap: 0.8rem;
}

.matching-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(180px, 280px);
  gap: 0.75rem;
  align-items: center;
  padding: 0.85rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fffaf1;
}

.matching-row p {
  margin: 0;
  line-height: 1.35;
}

.matching-row select {
  width: 100%;
  min-height: 44px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: white;
  color: var(--ink);
  font: inherit;
  padding: 0.55rem 0.65rem;
}

.matching-row.correct {
  border-color: var(--good);
  background: #e1f3e8;
}

.matching-row.incorrect {
  border-color: var(--bad);
  background: #f8e5e1;
}

.choice-button {
  display: grid;
  grid-template-columns: 2rem minmax(0, 1fr);
  align-items: center;
  gap: 0.7rem;
  width: 100%;
  padding: 0.9rem 1rem;
  background: #fffaf1;
  color: var(--ink);
  text-align: left;
}

.choice-letter {
  display: inline-grid;
  place-items: center;
  width: 2rem;
  height: 2rem;
  border-radius: 50%;
  background: var(--surface-strong);
  color: var(--accent-strong);
  font-weight: 900;
}

.choice-button.selected {
  border-color: var(--accent);
  background: #e2f1ed;
}

.choice-button.correct {
  border-color: var(--good);
  background: #e1f3e8;
}

.choice-button.incorrect {
  border-color: var(--bad);
  background: #f8e5e1;
}

.written-panel,
.answer-panel {
  margin: 1rem 0;
  padding: 1rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #faf6ee;
}

.answer-panel {
  border-color: rgba(33, 112, 106, 0.35);
  background: #f0faf6;
}

.answer-panel ul {
  margin: 0.3rem 0 0;
  padding-left: 1.2rem;
}

.explanation {
  margin: 0.8rem 0 0;
  color: var(--muted);
}

.review-panel h2 {
  margin-bottom: 0;
  font-size: 1.05rem;
}

.review-list {
  display: grid;
  gap: 0.55rem;
}

.review-item {
  width: 100%;
  padding: 0.75rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fffaf1;
  color: var(--ink);
  text-align: left;
  cursor: pointer;
}

.review-item strong {
  display: block;
  margin-bottom: 0.25rem;
  color: var(--accent-strong);
}

.empty-state {
  margin: 0;
  color: var(--muted);
}

.hidden {
  display: none !important;
}

@media (max-width: 1050px) {
  .control-panel {
    grid-template-columns: minmax(0, 1fr) minmax(240px, 360px);
    align-items: start;
  }

  .mode-grid {
    grid-column: span 2;
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (max-width: 700px) {
  .topbar {
    min-height: 54px;
  }

  .study-shell {
    padding: 0.75rem;
  }

  .control-panel {
    grid-template-columns: minmax(0, 1fr);
  }

  .mode-grid {
    grid-column: auto;
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .quiz-panel {
    padding: 1rem;
  }

  .list-header {
    display: grid;
  }

  .question-card h3 {
    font-size: 1.1rem;
  }

  .choice-button {
    grid-template-columns: 1.8rem minmax(0, 1fr);
    padding: 0.85rem;
  }

  .matching-row {
    grid-template-columns: minmax(0, 1fr);
  }
}