:root {
  --bg: #f4f1eb;
  --surface: #ffffff;
  --surface-muted: #ebe6dc;
  --text: #1c1917;
  --text-muted: #57534e;
  --primary: #1d4ed8;
  --primary-hover: #1e40af;
  --accent: #b45309;
  --success: #15803d;
  --success-bg: #dcfce7;
  --error: #b91c1c;
  --error-bg: #fee2e2;
  --info-bg: #dbeafe;
  --border: #d6d3d1;
  --shadow: 0 10px 40px rgba(28, 25, 23, 0.08);
  --radius: 16px;
  --radius-sm: 10px;
  --font: "DM Sans", system-ui, sans-serif;
  --font-display: "Fraunces", Georgia, serif;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  font-size: 16px;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font);
  color: var(--text);
  background:
    radial-gradient(circle at top left, rgba(29, 78, 216, 0.08), transparent 40%),
    radial-gradient(circle at bottom right, rgba(180, 83, 9, 0.08), transparent 35%),
    var(--bg);
}

.app {
  max-width: 1180px;
  margin: 0 auto;
  padding: 1.5rem;
}

.header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 2rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.875rem;
}

.brand-icon {
  font-size: 2rem;
  line-height: 1;
}

.brand h1 {
  margin: 0;
  font-family: var(--font-display);
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.brand p {
  margin: 0.15rem 0 0;
  color: var(--text-muted);
  font-size: 0.95rem;
}

.nav {
  display: flex;
  gap: 0.35rem;
  padding: 0.35rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 999px;
  box-shadow: var(--shadow);
}

.nav-btn {
  border: none;
  background: transparent;
  color: var(--text-muted);
  font: inherit;
  font-weight: 600;
  font-size: 0.9rem;
  padding: 0.55rem 1rem;
  border-radius: 999px;
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
}

.nav-btn:hover {
  color: var(--text);
  background: var(--surface-muted);
}

.nav-btn.active {
  background: var(--primary);
  color: #fff;
}

.panel-grid {
  display: grid;
  grid-template-columns: 1fr 1.1fr;
  gap: 1.5rem;
  align-items: start;
}

@media (max-width: 900px) {
  .panel-grid {
    grid-template-columns: 1fr;
  }
}

.card-area,
.reference,
.quiz-card,
.weak-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.card-area,
.quiz-card {
  padding: 1.5rem;
}

.reference,
.weak-panel {
  padding: 1.25rem 1.5rem 1.5rem;
}

.reference h2,
.weak-header h2 {
  margin: 0 0 1rem;
  font-family: var(--font-display);
  font-size: 1.25rem;
}

.toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.25rem;
}

.search input {
  width: min(100%, 220px);
  padding: 0.6rem 0.85rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font: inherit;
  background: var(--bg);
}

.search input:focus {
  outline: 2px solid rgba(29, 78, 216, 0.35);
  border-color: var(--primary);
}

.counter,
.score-meta {
  color: var(--text-muted);
  font-size: 0.875rem;
  font-weight: 600;
}

.flashcard-wrap {
  perspective: 1200px;
  margin-bottom: 1rem;
}

.flashcard {
  width: 100%;
  min-height: 260px;
  border: none;
  background: transparent;
  padding: 0;
  cursor: pointer;
  text-align: left;
}

.flashcard-inner {
  position: relative;
  width: 100%;
  min-height: 260px;
  transition: transform 0.55s cubic-bezier(0.4, 0, 0.2, 1);
  transform-style: preserve-3d;
}

.flashcard.flipped .flashcard-inner {
  transform: rotateY(180deg);
}

.flashcard-face {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 0.5rem;
  padding: 2rem;
  border-radius: var(--radius);
  backface-visibility: hidden;
  border: 2px solid var(--border);
}

.flashcard-face.front {
  background: linear-gradient(145deg, #fff, #f8fafc);
}

.flashcard-face.back {
  background: linear-gradient(145deg, #eff6ff, #dbeafe);
  transform: rotateY(180deg);
}

.flashcard[data-level="mastered"] .flashcard-face.front {
  border-color: #86efac;
}

.flashcard[data-level="weak"] .flashcard-face.front {
  border-color: #fca5a5;
}

.form-label {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.form-value {
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 2.75rem);
  font-weight: 700;
  color: var(--text);
}

.form-translation {
  margin-top: 0.35rem;
  font-size: 1.05rem;
  font-weight: 500;
  color: var(--accent);
  text-align: center;
  line-height: 1.4;
  max-width: 90%;
}

.form-row {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.25rem;
}

.hint {
  margin-top: 0.75rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.progress-bar {
  height: 6px;
  background: var(--surface-muted);
  border-radius: 999px;
  overflow: hidden;
  margin-bottom: 1.25rem;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), #3b82f6);
  border-radius: 999px;
  transition: width 0.25s ease;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
}

.btn {
  border: none;
  font: inherit;
  font-weight: 600;
  font-size: 0.925rem;
  padding: 0.65rem 1.1rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background 0.15s, transform 0.1s;
}

.btn:active {
  transform: scale(0.98);
}

.btn-primary {
  background: var(--primary);
  color: #fff;
}

.btn-primary:hover {
  background: var(--primary-hover);
}

.btn-secondary {
  background: var(--surface-muted);
  color: var(--text);
}

.btn-secondary:hover {
  background: #ddd6c8;
}

.btn-ghost {
  background: transparent;
  color: var(--text-muted);
}

.btn-ghost:hover {
  background: var(--surface-muted);
  color: var(--text);
}

.btn-sm {
  padding: 0.45rem 0.75rem;
  font-size: 0.825rem;
}

.table-wrap {
  max-height: 420px;
  overflow: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

th,
td {
  padding: 0.65rem 0.85rem;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

th {
  position: sticky;
  top: 0;
  background: var(--bg);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

tr:last-child td {
  border-bottom: none;
}

tr[data-level="mastered"] td:first-child {
  color: var(--success);
  font-weight: 600;
}

tr[data-level="weak"] td:first-child {
  color: var(--error);
  font-weight: 600;
}

.badge {
  display: inline-block;
  padding: 0.2rem 0.55rem;
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.badge-new {
  background: #f5f5f4;
  color: var(--text-muted);
}

.badge-learning {
  background: #fef3c7;
  color: #92400e;
}

.badge-mastered {
  background: var(--success-bg);
  color: var(--success);
}

.badge-weak {
  background: var(--error-bg);
  color: var(--error);
}

.quiz-card {
  max-width: 640px;
  margin: 0 auto;
}

.quiz-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.quiz-header h2 {
  margin: 0 0 0.35rem;
  font-family: var(--font-display);
}

.quiz-header p {
  margin: 0;
  color: var(--text-muted);
  font-size: 0.925rem;
}

.score-box {
  text-align: right;
}

.score-label {
  display: block;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.score-value {
  display: block;
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 700;
}

.prompt-box {
  text-align: center;
  padding: 1.5rem;
  margin-bottom: 1.25rem;
  border-radius: var(--radius);
  background: linear-gradient(145deg, #fff7ed, #ffedd5);
  border: 1px solid #fed7aa;
}

.prompt-word {
  display: block;
  margin-top: 0.35rem;
  font-family: var(--font-display);
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--accent);
}

.input-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-bottom: 1rem;
}

@media (max-width: 520px) {
  .input-grid {
    grid-template-columns: 1fr;
  }
}

.input-grid label {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-muted);
}

.input-grid input {
  padding: 0.75rem 0.9rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font: inherit;
  font-size: 1rem;
  background: var(--bg);
}

.input-grid input:focus {
  outline: 2px solid rgba(29, 78, 216, 0.35);
  border-color: var(--primary);
}

.input-grid input:disabled {
  opacity: 0.65;
}

.feedback {
  min-height: 1.5rem;
  margin: 0 0 1rem;
  font-size: 0.925rem;
}

.feedback.success {
  color: var(--success);
  font-weight: 600;
}

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

.feedback.info {
  color: var(--primary);
}

.results {
  text-align: center;
  padding: 2rem 1rem;
}

.results-badge {
  display: inline-block;
  padding: 0.35rem 0.75rem;
  border-radius: 999px;
  background: var(--info-bg);
  color: var(--primary);
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 1rem;
}

.results-score {
  margin: 0;
  font-family: var(--font-display);
  font-size: 3rem;
  font-weight: 700;
}

.results-percent {
  margin: 0.25rem 0 0.5rem;
  font-size: 1.25rem;
  color: var(--text-muted);
}

.results-message {
  margin: 0 0 1.5rem;
  font-size: 1.1rem;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  margin-bottom: 1.5rem;
}

@media (max-width: 640px) {
  .stats-grid {
    grid-template-columns: 1fr;
  }
}

.stat-card {
  padding: 1.25rem 1.5rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.stat-number {
  display: block;
  font-family: var(--font-display);
  font-size: 2.25rem;
  font-weight: 700;
}

.stat-label {
  color: var(--text-muted);
  font-size: 0.9rem;
}

.stat-card.accent-green .stat-number {
  color: var(--success);
}

.stat-card.accent-amber .stat-number {
  color: var(--accent);
}

.weak-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.weak-list li {
  display: grid;
  grid-template-columns: 1fr 1.4fr auto;
  gap: 0.75rem;
  padding: 0.75rem 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.9rem;
}

.weak-list li:last-child {
  border-bottom: none;
}

.weak-list li span:first-child {
  font-weight: 700;
}

.weak-list li span:nth-child(2) {
  color: var(--text-muted);
}

.weak-list li span:last-child {
  font-weight: 700;
  color: var(--error);
}

.weak-list li.empty {
  display: block;
  color: var(--text-muted);
  font-style: italic;
}

.weak-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  margin-bottom: 0.5rem;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}