:root {
  color-scheme: light;
  --ink: #1f2a24;
  --muted: #6f786f;
  --cream: #f6f1e4;
  --card: #fffdf7;
  --line: #e6dfcd;
  --green: #1b4d3e;
  --green-soft: #e3ece6;
  --red: #a63d32;
  --red-soft: #f7e3df;
  --gold: #c98b2b;
  --radius: 16px;
  font-family: "Segoe UI", "Nirmala UI", "Hiragino Sans", "Yu Gothic", "Meiryo", Arial, sans-serif;
  text-rendering: optimizeLegibility;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-width: 320px;
  min-height: 100vh;
  color: var(--ink);
  background: var(--cream);
}

button,
input {
  font: inherit;
}

button {
  cursor: pointer;
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

:focus-visible {
  outline: 3px solid var(--gold);
  outline-offset: 2px;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
  padding: 0 5vw;
  border-bottom: 1px solid var(--line);
  background: rgba(255, 253, 247, 0.75);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-weight: 800;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 32px;
  height: 32px;
  border-radius: 9px;
  color: #fff;
  background: var(--green);
}

.brand-light {
  color: var(--muted);
  font-weight: 600;
}

.back-link {
  color: var(--green);
  font-weight: 700;
  text-decoration: none;
}

.layout {
  display: grid;
  grid-template-columns: 280px minmax(0, 1fr);
  gap: 40px;
  max-width: 1200px;
  margin: 0 auto;
  padding: 36px 5vw 60px;
}

.sidebar h1 {
  margin: 6px 0 26px;
  font-size: 26px;
  line-height: 1.2;
  letter-spacing: -0.5px;
}

.eyebrow,
.nav-label {
  margin: 0;
  color: var(--muted);
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 1.4px;
}

.nav-label {
  margin: 20px 0 9px;
}

.group-tabs {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4px;
  padding: 4px;
  border-radius: 12px;
  background: #ebe4d2;
}

.group-tab,
.category-tab,
.mode-tab {
  border: 0;
  color: var(--ink);
  background: transparent;
  font-weight: 700;
  transition: background 150ms, color 150ms;
}

.group-tab {
  padding: 9px;
  border-radius: 9px;
}

.category-list {
  display: grid;
  gap: 3px;
}

.category-tab {
  display: flex;
  justify-content: space-between;
  gap: 8px;
  padding: 10px 12px;
  border-radius: 10px;
  text-align: left;
}

.category-tab small {
  color: var(--muted);
  font-weight: 500;
}

.group-tab:hover,
.category-tab:hover,
.mode-tab:hover {
  background: var(--green-soft);
}

.group-tab.active,
.category-tab.active,
.mode-tab.active {
  color: #fff;
  background: var(--green);
}

.category-tab.active small {
  color: #cfe0d6;
}

.reset-button {
  margin-top: 22px;
  color: var(--muted);
}

.content-heading {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 18px;
}

.content-heading h2 {
  margin: 4px 0 0;
  font-size: 34px;
  letter-spacing: -0.8px;
}

.progress-summary {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
}

.mode-tabs {
  display: inline-flex;
  gap: 4px;
  margin-bottom: 22px;
  padding: 4px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--card);
}

.mode-tab {
  padding: 9px 20px;
  border-radius: 10px;
}

.mode-panel:focus {
  outline: none;
}

.card,
.flashcard {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card);
  box-shadow: 0 10px 30px rgba(52, 44, 20, 0.06);
}

.card {
  padding: 26px;
}

.primary-button,
.secondary-button,
.text-button {
  border-radius: 10px;
  font-weight: 700;
}

.primary-button {
  padding: 11px 20px;
  border: 1px solid var(--green);
  color: #fff;
  background: var(--green);
}

.secondary-button {
  padding: 10px 16px;
  border: 1px solid var(--line);
  color: var(--ink);
  background: var(--card);
}

.secondary-button[aria-pressed="true"] {
  border-color: var(--green);
  color: var(--green);
  background: var(--green-soft);
}

.text-button {
  padding: 6px 0;
  border: 0;
  color: var(--green);
  background: none;
  text-decoration: underline;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-top: 18px;
}

.counter {
  margin: 0 0 12px;
  color: var(--muted);
  font-size: 14px;
  font-weight: 700;
}

.flashcard {
  display: grid;
  align-content: center;
  justify-items: center;
  gap: 10px;
  width: 100%;
  min-height: 300px;
  padding: 34px;
  color: var(--ink);
  text-align: center;
  transition: transform 180ms, box-shadow 180ms;
}

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

.flashcard.flipped {
  border-color: var(--green);
  background: var(--green-soft);
}

.card-label {
  color: var(--muted);
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 1.4px;
}

.card-term {
  font-size: clamp(34px, 7vw, 54px);
  line-height: 1.15;
}

.card-reading {
  color: var(--green);
  font-size: 20px;
}

.card-romaji {
  color: var(--muted);
  font-style: italic;
}

.card-english {
  font-size: clamp(24px, 4vw, 32px);
}

.card-note {
  max-width: 520px;
  margin: 0;
  color: #4b554e;
  line-height: 1.6;
}

.card-hint {
  margin-top: 8px;
  color: var(--muted);
  font-size: 13px;
}

.known-badge {
  color: var(--green);
  font-size: 13px;
  font-weight: 800;
}

.question-term {
  margin: 6px 0 2px;
  font-size: clamp(30px, 6vw, 44px);
}

.question-reading {
  margin: 0 0 18px;
  color: var(--green);
}

.question-reading.pending {
  color: var(--muted);
  font-size: 0.85rem;
  font-style: italic;
}

.options {
  display: grid;
  gap: 10px;
}

.option {
  padding: 13px 16px;
  border: 1px solid var(--line);
  border-radius: 12px;
  color: var(--ink);
  background: #fff;
  font-weight: 600;
  text-align: left;
}

.option:hover:not(:disabled) {
  border-color: var(--green);
}

.option:disabled {
  opacity: 1;
}

.option.correct {
  border-color: var(--green);
  background: var(--green-soft);
}

.option.incorrect {
  border-color: var(--red);
  background: var(--red-soft);
}

.feedback {
  margin-top: 16px;
  padding: 14px 16px;
  border-radius: 12px;
  line-height: 1.55;
}

.feedback.correct {
  background: var(--green-soft);
}

.feedback.incorrect {
  background: var(--red-soft);
}

.feedback p {
  margin: 4px 0 0;
}

.score-big {
  margin: 4px 0;
  color: var(--green);
  font-size: 58px;
  font-weight: 800;
  letter-spacing: -2px;
}

.exam-header {
  position: sticky;
  top: 0;
  z-index: 1;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 16px;
  padding: 12px 16px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--card);
}

.exam-timer {
  margin: 0;
  color: var(--green);
  font-size: 22px;
  font-variant-numeric: tabular-nums;
  font-weight: 800;
}

.exam-timer.warning {
  color: var(--red);
}

.exam-question {
  margin: 0 0 14px;
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card);
}

.exam-question legend {
  padding: 0 6px;
  font-size: 18px;
  font-weight: 700;
}

.exam-option {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 8px;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #fff;
  cursor: pointer;
}

.exam-option:has(input:checked) {
  border-color: var(--green);
  background: var(--green-soft);
}

.exam-option input {
  accent-color: var(--green);
}

.review-list {
  display: grid;
  gap: 10px;
  margin: 18px 0 0;
  padding: 0;
  list-style: none;
}

.review-item {
  padding: 14px 16px;
  border-left: 4px solid var(--green);
  border-radius: 10px;
  background: var(--green-soft);
}

.review-item.incorrect {
  border-left-color: var(--red);
  background: var(--red-soft);
}

.review-item p {
  margin: 4px 0 0;
}

.empty-state,
.status-message {
  padding: 40px;
  text-align: center;
}

.status-message.error {
  color: var(--red);
}

.disclaimer {
  margin-top: 28px;
  color: var(--muted);
  font-size: 13px;
}

@media (max-width: 860px) {
  .layout {
    grid-template-columns: minmax(0, 1fr);
    gap: 18px;
  }

  .sidebar h1 {
    margin-bottom: 8px;
    font-size: 22px;
  }

  .category-list {
    display: flex;
    gap: 6px;
    overflow-x: auto;
    padding-bottom: 6px;
  }

  .category-tab {
    flex: none;
    border: 1px solid var(--line);
    background: var(--card);
  }

  .category-tab small {
    display: none;
  }

  .mode-tabs {
    display: flex;
  }

  .mode-tab {
    flex: 1;
    padding: 9px 8px;
  }
}

@media (prefers-reduced-motion: reduce) {
  * {
    transition: none !important;
  }
}