:root {
  --bg: #0f1419;
  --bg-card: #1a2332;
  --bg-elevated: #243044;
  --border: #2d3a4f;
  --text: #e8eef6;
  --text-muted: #8b9bb4;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --success: #22c55e;
  --danger: #ef4444;
  --warning: #f59e0b;
  --radius: 14px;
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.35);
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { height: 100%; }

body {
  min-height: 100%;
  font-family: var(--font);
  background: radial-gradient(ellipse at top, #1a2740 0%, var(--bg) 55%);
  color: var(--text);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

.app {
  max-width: 720px;
  margin: 0 auto;
  padding: 1rem 1rem 3rem;
}

header.app-header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 1.25rem;
  padding-top: 0.5rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.65rem;
}

.brand-mark {
  width: 40px;
  height: 40px;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--accent), #8b5cf6);
  display: grid;
  place-items: center;
  font-weight: 700;
  font-size: 1.1rem;
  box-shadow: 0 4px 14px rgba(59, 130, 246, 0.35);
}

.brand h1 {
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.brand p {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.header-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
}

select, button, input[type="text"] {
  font: inherit;
  color: var(--text);
}

select, input[type="text"] {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.55rem 0.75rem;
  outline: none;
}

select:focus, input[type="text"]:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.25);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  border: none;
  border-radius: 10px;
  padding: 0.65rem 1rem;
  background: var(--accent);
  color: #fff;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, transform 0.1s;
  text-decoration: none;
}

.btn:hover { background: var(--accent-hover); }
.btn:active { transform: scale(0.98); }
.btn:disabled { opacity: 0.45; cursor: not-allowed; }

.btn-ghost {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text);
}
.btn-ghost:hover { background: var(--bg-elevated); }

.btn-success { background: var(--success); }
.btn-success:hover { background: #16a34a; }
.btn-danger { background: var(--danger); }
.btn-danger:hover { background: #dc2626; }
.btn-icon {
  width: 42px;
  height: 42px;
  padding: 0;
  border-radius: 12px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  font-size: 1.1rem;
}

.stats-bar {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.65rem;
  margin-bottom: 1.25rem;
}

.stat {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.85rem 0.9rem;
  text-align: center;
}

.stat .label {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.stat .value {
  font-size: 1.35rem;
  font-weight: 700;
  margin-top: 0.15rem;
}

.panel {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  box-shadow: var(--shadow);
  margin-bottom: 1rem;
}

.panel h2 {
  font-size: 1rem;
  margin-bottom: 0.85rem;
}

.setup-grid {
  display: grid;
  gap: 0.85rem;
}

.setup-grid label {
  display: grid;
  gap: 0.35rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.mode-tabs {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.mode-tab {
  padding: 0.7rem 0.5rem;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--bg-elevated);
  color: var(--text-muted);
  font-weight: 600;
  font-size: 0.85rem;
  cursor: pointer;
}

.mode-tab.active {
  background: rgba(59, 130, 246, 0.18);
  border-color: var(--accent);
  color: #fff;
}

.hidden { display: none !important; }

/* Flashcard */
.flash-area {
  perspective: 1000px;
  margin: 0.5rem 0 1rem;
}

.flash-card {
  min-height: 220px;
  background: linear-gradient(160deg, #243044, #1a2332);
  border: 1px solid var(--border);
  border-radius: 18px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  cursor: pointer;
  position: relative;
  transition: transform 0.25s, border-color 0.2s;
  user-select: none;
}

.flash-card:hover { border-color: var(--accent); }
.flash-card.flipped { border-color: var(--success); }

.flash-side {
  text-align: center;
  width: 100%;
}

.flash-lang {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.flash-word {
  font-size: clamp(1.6rem, 6vw, 2.4rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  word-break: break-word;
}

.flash-hint {
  margin-top: 1rem;
  font-size: 0.8rem;
  color: var(--text-muted);
}

.flash-cat {
  position: absolute;
  top: 0.85rem;
  left: 1rem;
  font-size: 0.7rem;
  color: var(--text-muted);
  background: rgba(255,255,255,0.05);
  padding: 0.2rem 0.55rem;
  border-radius: 999px;
}

.card-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem;
  justify-content: center;
  margin-top: 0.25rem;
}

.progress-line {
  height: 6px;
  background: var(--bg-elevated);
  border-radius: 999px;
  overflow: hidden;
  margin: 0.75rem 0 0.25rem;
}

.progress-line > span {
  display: block;
  height: 100%;
  background: linear-gradient(90deg, var(--accent), #8b5cf6);
  width: 0%;
  transition: width 0.25s;
}

.session-meta {
  display: flex;
  justify-content: space-between;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

/* Quiz */
.quiz-prompt {
  text-align: center;
  margin: 0.5rem 0 1.25rem;
}

.quiz-prompt .q-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.quiz-prompt .q-word {
  font-size: clamp(1.5rem, 5vw, 2.1rem);
  font-weight: 700;
  margin-top: 0.35rem;
}

.choices {
  display: grid;
  gap: 0.55rem;
}

.choice {
  width: 100%;
  text-align: left;
  padding: 0.9rem 1rem;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--bg-elevated);
  color: var(--text);
  font-weight: 500;
  cursor: pointer;
}

.choice:hover:not(:disabled) { border-color: var(--accent); }
.choice.correct {
  border-color: var(--success);
  background: rgba(34, 197, 94, 0.15);
}
.choice.wrong {
  border-color: var(--danger);
  background: rgba(239, 68, 68, 0.12);
}

.typing-row {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.typing-row input {
  flex: 1 1 180px;
  min-width: 0;
}

.feedback {
  margin-top: 0.85rem;
  padding: 0.75rem 0.9rem;
  border-radius: 10px;
  font-size: 0.9rem;
  display: none;
}

.feedback.show { display: block; }
.feedback.ok {
  background: rgba(34, 197, 94, 0.12);
  border: 1px solid rgba(34, 197, 94, 0.35);
  color: #86efac;
}
.feedback.bad {
  background: rgba(239, 68, 68, 0.12);
  border: 1px solid rgba(239, 68, 68, 0.35);
  color: #fca5a5;
}

.donation {
  text-align: center;
  padding: 1.25rem;
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  background: rgba(255,255,255,0.02);
  margin-top: 1.5rem;
}

.donation p {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-bottom: 0.75rem;
}

.footer-note {
  text-align: center;
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 1.5rem;
}

.empty-state {
  text-align: center;
  padding: 2rem 1rem;
  color: var(--text-muted);
}

@media (max-width: 480px) {
  .stats-bar { grid-template-columns: 1fr; }
  .mode-tabs { grid-template-columns: 1fr; }
  .brand h1 { font-size: 1rem; }
}

/* Legal pages */
.legal-banner {
  background: rgba(245, 158, 11, 0.12);
  border: 1px solid rgba(245, 158, 11, 0.4);
  color: #fbbf24;
  border-radius: 10px;
  padding: 0.75rem 0.9rem;
  font-size: 0.85rem;
  margin-bottom: 1.25rem;
}

.legal-page {
  max-width: 720px;
  margin: 0 auto;
  padding: 1rem 1rem 3rem;
}

.legal-page h1 {
  font-size: 1.5rem;
  margin-bottom: 0.35rem;
  letter-spacing: -0.02em;
}

.legal-page .legal-lead {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-bottom: 1.25rem;
}

.legal-page h2 {
  font-size: 1.05rem;
  margin: 1.5rem 0 0.55rem;
}

.legal-page p, .legal-page li {
  color: var(--text);
  font-size: 0.95rem;
  margin-bottom: 0.65rem;
}

.legal-page ul {
  padding-left: 1.2rem;
  margin-bottom: 0.75rem;
}

.legal-page a {
  color: #93c5fd;
}

.placeholder {
  background: rgba(239, 68, 68, 0.15);
  border: 1px dashed rgba(239, 68, 68, 0.55);
  color: #fca5a5;
  padding: 0.05rem 0.35rem;
  border-radius: 4px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.85em;
  white-space: nowrap;
}

.legal-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.25rem;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  justify-content: center;
  margin-top: 0.75rem;
  font-size: 0.8rem;
}

.footer-links a {
  color: var(--text-muted);
  text-decoration: none;
}

.footer-links a:hover {
  color: #93c5fd;
  text-decoration: underline;
}

.en-summary {
  margin-top: 2rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--border);
}

.en-summary h2 {
  margin-top: 0;
}