:root {
  --bg: #f5f1ea;
  --panel: rgba(255, 255, 255, 0.86);
  --panel-strong: #ffffff;
  --text: #2f241d;
  --muted: #6c5a4d;
  --primary: #9d5c63;
  --primary-dark: #7e4148;
  --accent: #d6b98b;
  --success: #2f8f62;
  --error: #b54747;
  --shadow: 0 18px 40px rgba(68, 42, 28, 0.12);
  font-family: "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background: radial-gradient(circle at top left, #fff3e3 0, #f7e4dd 32%, #efe4dd 100%);
  color: var(--text);
}

button,
select,
textarea {
  font: inherit;
}

.app-shell {
  width: min(1100px, calc(100% - 32px));
  margin: 32px auto;
}

.hero {
  display: flex;
  justify-content: space-between;
  gap: 24px;
  align-items: stretch;
  background: linear-gradient(135deg, rgba(255,255,255,0.9), rgba(255,248,241,0.9));
  padding: 28px;
  border-radius: 24px;
  box-shadow: var(--shadow);
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--primary);
  font-weight: 700;
  font-size: 0.85rem;
  margin-bottom: 8px;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1 {
  font-size: clamp(2rem, 3vw, 3.4rem);
  margin-bottom: 12px;
}

.subtitle {
  color: var(--muted);
  max-width: 60ch;
  margin-bottom: 0;
}

.score-card {
  min-width: 200px;
  background: linear-gradient(160deg, var(--primary), var(--primary-dark));
  color: white;
  border-radius: 20px;
  padding: 20px;
  display: grid;
  align-content: center;
  box-shadow: var(--shadow);
}

.score-card strong {
  font-size: 3rem;
  line-height: 1;
  margin: 8px 0;
}

.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 24px 0 18px;
}

.tab,
.secondary-button,
.option-button {
  border: none;
  border-radius: 14px;
  padding: 12px 16px;
  cursor: pointer;
  transition: transform 0.15s ease, background-color 0.15s ease, color 0.15s ease, box-shadow 0.15s ease;
}

.tab {
  background: rgba(255,255,255,0.7);
  color: var(--text);
  box-shadow: var(--shadow);
  font-weight: 600;
}

.tab.active,
.tab:hover,
.secondary-button:hover,
.option-button:hover {
  transform: translateY(-2px);
}

.tab.active {
  background: var(--primary);
  color: white;
}

.panel {
  display: none;
  background: var(--panel);
  backdrop-filter: blur(10px);
  border-radius: 24px;
  padding: 24px;
  box-shadow: var(--shadow);
}

.panel.active {
  display: block;
}

.section-header {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  align-items: center;
  margin-bottom: 20px;
}

select,
.secondary-button,
textarea {
  border: 1px solid rgba(92, 63, 48, 0.16);
  background: var(--panel-strong);
}

select,
.secondary-button {
  padding: 12px 14px;
  border-radius: 14px;
}

.secondary-button {
  color: var(--text);
  font-weight: 600;
}

.study-card,
.quiz-box,
.structure-box,
.prompt-box {
  background: rgba(255,255,255,0.78);
  border-radius: 20px;
  padding: 22px;
}

.study-card h3 {
  margin-bottom: 10px;
}

.info-grid,
.structure-grid,
.prompt-grid {
  display: grid;
  gap: 16px;
}

.info-grid {
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
}

.structure-grid {
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
}

.info-pill {
  background: #fffaf5;
  border: 1px solid rgba(157, 92, 99, 0.15);
  border-radius: 16px;
  padding: 16px;
}

.info-pill span,
.quiz-label {
  display: block;
  color: var(--primary);
  font-weight: 700;
  font-size: 0.88rem;
  margin-bottom: 8px;
}

.option-grid,
.stacked-options {
  display: grid;
  gap: 12px;
}

.option-grid {
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  margin-top: 18px;
}

.option-button {
  text-align: left;
  background: #fffaf5;
  border: 1px solid rgba(92, 63, 48, 0.12);
  color: var(--text);
}

.option-button.correct {
  background: rgba(47, 143, 98, 0.14);
  border-color: rgba(47, 143, 98, 0.4);
  color: var(--success);
}

.option-button.wrong {
  background: rgba(181, 71, 71, 0.12);
  border-color: rgba(181, 71, 71, 0.4);
  color: var(--error);
}

.feedback {
  min-height: 28px;
  margin-top: 18px;
  font-weight: 600;
}

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

.feedback.error {
  color: var(--error);
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  padding: 0;
  list-style: none;
}

.tag-list li {
  background: rgba(214, 185, 139, 0.28);
  border-radius: 999px;
  padding: 8px 12px;
}

textarea {
  width: 100%;
  padding: 16px;
  border-radius: 16px;
  resize: vertical;
  color: var(--text);
}

.tip-box {
  background: #fffaf5;
  border-left: 5px solid var(--accent);
  padding: 14px 16px;
  border-radius: 16px;
  margin-top: 16px;
}

.prompt-box {
  display: grid;
  gap: 16px;
}

.rubric-box,
.evaluation-box {
  margin-top: 0;
}

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

.pill-title {
  display: block;
  color: var(--primary);
  font-weight: 700;
  font-size: 0.88rem;
  margin-bottom: 10px;
}

.timer-pill {
  display: grid;
  gap: 8px;
}

.words-row {
  display: flex;
  align-items: stretch;
  gap: 12px;
}

.words-stat {
  flex: 1;
  display: grid;
  place-items: center;
  min-height: 72px;
  text-align: center;
  background: rgba(255,255,255,0.65);
  border: 1px solid rgba(157, 92, 99, 0.12);
  border-radius: 16px;
  padding: 10px;
}

.words-stat strong {
  font-size: 1.35rem;
  line-height: 1;
}

.words-stat small {
  color: var(--muted);
  font-size: 0.82rem;
  margin-top: 4px;
}

.current-stat {
  background: linear-gradient(160deg, rgba(157, 92, 99, 0.12), rgba(255,255,255,0.8));
}

.stat-caption {
  color: var(--muted);
  font-size: 0.74rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 6px;
}

.timer-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.timer-display {
  min-width: 108px;
  display: grid;
  gap: 6px;
}

.timer-display strong {
  font-size: 1.45rem;
  line-height: 1;
}

.timer-controls {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 8px;
}

.timer-presets {
  display: flex;
  gap: 6px;
  align-items: center;
}

.timer-preset,
.timer-start-button {
  border: 1px solid rgba(92, 63, 48, 0.16);
  background: rgba(255, 255, 255, 0.72);
  color: var(--text);
  border-radius: 999px;
  padding: 5px 9px;
  cursor: pointer;
  font-weight: 700;
  min-width: 46px;
  line-height: 1;
  font-size: 0.9rem;
}

.timer-preset.active {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

.timer-start-button {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
  min-width: 56px;
}

.timer-note {
  margin: 0;
  color: var(--muted);
  font-size: 0.82rem;
}

.timer-note.success {
  color: var(--success);
}

.timer-note.error {
  color: var(--error);
}

.compact-header {
  margin-bottom: 12px;
}

.ghost-button {
  background: transparent;
}

.history-box {
  background: #fffaf5;
  border: 1px solid rgba(157, 92, 99, 0.14);
  border-radius: 20px;
  padding: 18px;
}

.evaluation-box {
  background: #fffaf5;
  border: 1px solid rgba(157, 92, 99, 0.14);
  border-radius: 20px;
  padding: 18px;
}

.evaluation-summary h3 {
  margin-bottom: 8px;
}

.evaluation-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 12px;
  margin-top: 16px;
}

.evaluation-card {
  background: rgba(255,255,255,0.88);
  border-radius: 16px;
  padding: 14px;
  border: 1px solid rgba(92, 63, 48, 0.1);
}

.evaluation-card strong {
  display: block;
  font-size: 1.2rem;
  margin: 4px 0 8px;
}

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

.evaluation-tips {
  margin-top: 16px;
}

.evaluation-tips ul {
  margin: 10px 0 0;
  padding-left: 18px;
}

.history-list {
  display: grid;
  gap: 12px;
}

.history-item {
  background: rgba(255,255,255,0.88);
  border-radius: 16px;
  padding: 14px;
  border: 1px solid rgba(92, 63, 48, 0.1);
}

.history-item strong,
.history-item span {
  display: block;
}

.history-item p {
  color: var(--muted);
  margin: 8px 0 0;
}

.history-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  color: var(--muted);
  font-size: 0.95rem;
  margin-top: 8px;
}

/* ── Dark mode ─────────────────────────────────────────────── */
.dark-toggle {
  margin-top: 10px;
  background: rgba(255,255,255,0.15);
  border: 1px solid rgba(255,255,255,0.3);
  color: white;
  border-radius: 999px;
  padding: 5px 12px;
  cursor: pointer;
  font-size: 0.82rem;
  font-weight: 600;
  width: 100%;
  transition: background 0.2s;
}
.dark-toggle:hover {
  background: rgba(255,255,255,0.28);
}

body.dark-mode {
  --bg: #1a1310;
  --panel: rgba(36, 26, 22, 0.92);
  --panel-strong: #2a1e19;
  --text: #f0e6dc;
  --muted: #a89080;
  --primary: #c97e87;
  --primary-dark: #a85e67;
  --accent: #8a6840;
  --success: #4ab882;
  --error: #d96b6b;
  background: radial-gradient(circle at top left, #2a1a12 0, #1e1210 50%, #181010 100%);
}
body.dark-mode .hero {
  background: linear-gradient(135deg, rgba(42,26,18,0.95), rgba(30,18,14,0.95));
}
body.dark-mode .panel,
body.dark-mode .study-card,
body.dark-mode .quiz-box,
body.dark-mode .structure-box,
body.dark-mode .history-box,
body.dark-mode .evaluation-box {
  background: rgba(36, 26, 22, 0.95);
}
body.dark-mode .info-pill,
body.dark-mode .option-button,
body.dark-mode .words-stat,
body.dark-mode .evaluation-card,
body.dark-mode .history-item {
  background: rgba(48, 34, 26, 0.9);
  border-color: rgba(200, 120, 100, 0.18);
}
body.dark-mode .tab {
  background: rgba(48, 34, 26, 0.8);
  color: var(--text);
}
body.dark-mode .tab.active {
  background: var(--primary);
  color: #fff;
}
body.dark-mode select,
body.dark-mode textarea {
  background: var(--panel-strong);
  color: var(--text);
  border-color: rgba(200, 120, 100, 0.2);
}
body.dark-mode .tip-box {
  background: rgba(48, 34, 26, 0.8);
}
body.dark-mode .example-box {
  background: rgba(48, 34, 26, 0.8);
  border-color: rgba(200, 120, 100, 0.2);
}
body.dark-mode .flashcard-front {
  background: linear-gradient(135deg, #2a1e19, #3a2820);
}
body.dark-mode .flashcard-back {
  background: linear-gradient(135deg, #1e2a24, #243220);
}
body.dark-mode .prompt-box {
  background: rgba(36, 26, 22, 0.95);
}
body.dark-mode .secondary-button {
  background: rgba(48, 34, 26, 0.8);
  color: var(--text);
  border-color: rgba(200, 120, 100, 0.2);
}
body.dark-mode .ghost-button {
  background: transparent;
  border-color: rgba(200, 120, 100, 0.2);
}
body.dark-mode .timer-preset {
  background: rgba(48, 34, 26, 0.8);
  color: var(--text);
  border-color: rgba(200, 120, 100, 0.2);
}
body.dark-mode .timer-preset.active {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}
body.dark-mode .timer-start-button {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}
body.dark-mode .tag-list li {
  background: rgba(140, 104, 64, 0.22);
}
body.dark-mode .current-stat {
  background: linear-gradient(160deg, rgba(200, 126, 135, 0.15), rgba(48, 34, 26, 0.8));
}
body.dark-mode .quiz-stats-badge {
  background: rgba(200, 126, 135, 0.15);
  border-color: rgba(200, 120, 100, 0.25);
}
body.dark-mode .word-progress-bar {
  background: rgba(200, 126, 135, 0.15);
}

/* ── Word progress bar ──────────────────────────────────────── */
.word-progress-bar {
  margin-top: 10px;
  height: 6px;
  border-radius: 999px;
  background: rgba(157, 92, 99, 0.14);
  overflow: hidden;
}
.word-progress-fill {
  height: 100%;
  width: 0%;
  border-radius: 999px;
  background: var(--error);
  transition: width 0.4s ease, background 0.4s ease;
}
.word-progress-fill.close {
  background: #d48b3b;
}
.word-progress-fill.done {
  background: var(--success);
}

/* ── Quiz stats badge ───────────────────────────────────────── */
.quiz-stats-badge {
  background: rgba(157, 92, 99, 0.12);
  border: 1px solid rgba(157, 92, 99, 0.2);
  color: var(--primary);
  border-radius: 999px;
  padding: 5px 12px;
  font-size: 0.85rem;
  font-weight: 600;
}
.kviz-controls {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

/* ── Example box ────────────────────────────────────────────── */
.example-box {
  background: #fffaf5;
  border: 1px solid rgba(157, 92, 99, 0.15);
  border-radius: 16px;
  padding: 14px 16px;
  margin-top: 16px;
}
.example-box summary {
  cursor: pointer;
  color: var(--primary);
  font-weight: 700;
  font-size: 0.92rem;
  list-style: none;
  user-select: none;
}
.example-box summary::before {
  content: "▶ ";
  font-size: 0.75rem;
}
.example-box[open] summary::before {
  content: "▼ ";
}
.example-grid {
  display: grid;
  gap: 12px;
  margin-top: 12px;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
}
.example-part {
  background: rgba(255,255,255,0.88);
  border-radius: 12px;
  padding: 12px;
  border: 1px solid rgba(92,63,48,0.1);
}
.example-part p {
  color: var(--muted);
  font-size: 0.9rem;
  margin: 6px 0 0;
  font-style: italic;
}
.example-label {
  color: var(--primary);
  font-weight: 700;
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* ── Flashcards ─────────────────────────────────────────────── */
.flashcard-area {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 24px;
  padding: 16px 0;
}
.flashcard {
  width: 100%;
  max-width: 560px;
  height: 220px;
  perspective: 1000px;
  cursor: pointer;
  position: relative;
}
.flashcard-inner-wrap {
  width: 100%;
  height: 100%;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.45s cubic-bezier(0.4,0,0.2,1);
}
#flashcard-inner {
  width: 100%;
  max-width: 560px;
  height: 220px;
  cursor: pointer;
  position: relative;
  perspective: 1000px;
  outline: none;
}
#flashcard-inner .flashcard-face {
  position: absolute;
  inset: 0;
  border-radius: 20px;
  padding: 28px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  transition: transform 0.45s cubic-bezier(0.4,0,0.2,1), opacity 0.45s;
  box-shadow: var(--shadow);
}
.flashcard-front {
  background: linear-gradient(135deg, #fff8f2, #ffe8e0);
  border: 1px solid rgba(157, 92, 99, 0.2);
  transform: rotateY(0deg);
  opacity: 1;
}
.flashcard-back {
  background: linear-gradient(135deg, #f0fff8, #e0ffee);
  border: 1px solid rgba(47, 143, 98, 0.2);
  transform: rotateY(180deg);
  opacity: 0;
}
#flashcard-inner.flipped .flashcard-front {
  transform: rotateY(-180deg);
  opacity: 0;
}
#flashcard-inner.flipped .flashcard-back {
  transform: rotateY(0deg);
  opacity: 1;
}
.fc-label {
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 12px;
}
.flashcard-front p,
.flashcard-back p {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
  margin: 0;
  line-height: 1.5;
}
.fc-nav {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
}
.fc-controls {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

@media (max-width: 760px) {
  .app-shell {
    width: min(100% - 20px, 1100px);
    margin: 20px auto;
  }

  .hero,
  .section-header {
    flex-direction: column;
    align-items: stretch;
  }

  .score-card {
    min-width: 0;
  }

  .prompt-actions {
    flex-direction: column;
  }

  .timer-row {
    flex-direction: column;
    align-items: stretch;
  }

  .timer-controls {
    justify-content: space-between;
  }

  .timer-presets {
    flex-wrap: wrap;
  }

  .words-row {
    flex-direction: column;
    align-items: stretch;
  }

  .info-grid {
    grid-template-columns: 1fr;
  }

  .evaluation-grid {
    grid-template-columns: 1fr;
  }

  .example-grid {
    grid-template-columns: 1fr;
  }

  .flashcard,
  #flashcard-inner {
    height: 180px;
  }

  .kviz-controls {
    flex-direction: column;
    align-items: flex-start;
  }
}