:root {
  --bg: #f5f3ef;
  --surface: #ffffff;
  --ink: #24211c;
  --ink-soft: #6b6560;
  --border: #e4ded4;
  --accent: #b5473a;
  --accent-ink: #ffffff;
  --accent-soft: #f1ded9;
  --l0: #d9d4cb;
  --l1: #e8b4a8;
  --l2: #eecf8f;
  --l3: #d7d98a;
  --l4: #9fc98a;
  --l5: #5a9e6f;
  --radius: 16px;
  --shadow: 0 1px 2px rgba(30,25,15,0.06), 0 8px 24px rgba(30,25,15,0.06);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1a1815;
    --surface: #242019;
    --ink: #efe9e0;
    --ink-soft: #a39a8d;
    --border: #38332a;
    --accent: #e07a63;
    --accent-ink: #1a1815;
    --accent-soft: #3a2620;
    --l0: #3a352c;
    --l1: #6b3f36;
    --l2: #6b5730;
    --l3: #52562c;
    --l4: #375c3e;
    --l5: #2f7a4d;
    --shadow: 0 1px 2px rgba(0,0,0,0.3), 0 8px 24px rgba(0,0,0,0.3);
  }
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  min-height: 100vh;
}

#app {
  max-width: 480px;
  margin: 0 auto;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  padding: 20px 20px 40px;
}

.screen.hidden { display: none; }
.hidden { display: none !important; }

/* Header */
.app-header { text-align: center; margin: 24px 0 20px; }
.app-header h1 { font-size: 1.6rem; margin: 0 0 4px; letter-spacing: -0.01em; }
.subtitle { color: var(--ink-soft); margin: 0; font-size: 0.9rem; }

.sub-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 8px 0 24px;
}
.sub-header h2 { margin: 0; font-size: 1.3rem; }

.btn-back {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--ink);
  width: 40px;
  height: 40px;
  border-radius: 12px;
  font-size: 1.1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
}
.btn-back:hover { background: var(--accent-soft); }

/* Stats card */
.stats-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
}
.stats-row { display: flex; justify-content: space-around; margin-bottom: 16px; }
.stat { text-align: center; }
.stat-num { font-size: 1.7rem; font-weight: 700; }
.stat-label { font-size: 0.78rem; color: var(--ink-soft); margin-top: 2px; }

.level-bar {
  height: 10px;
  border-radius: 6px;
  overflow: hidden;
  display: flex;
  background: var(--l0);
}
.level-bar .seg { height: 100%; }
.seg-0 { background: var(--l0); }
.seg-1 { background: var(--l1); }
.seg-2 { background: var(--l2); }
.seg-3 { background: var(--l3); }
.seg-4 { background: var(--l4); }
.seg-5 { background: var(--l5); }

/* Level chooser — one card per level, each with its own progress bar */
.level-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 24px;
}

.level-card {
  display: block;
  width: 100%;
  text-align: left;
  font: inherit;
  color: inherit;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 18px;
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: border-color 0.15s ease, transform 0.1s ease;
}
.level-card:hover { border-color: var(--accent); }
.level-card:active { transform: scale(0.995); }

/* The selected level is the one Study and Flashcards will run on, so it is
   marked with the accent rather than a subtle tint. */
.level-card.selected {
  border-color: var(--accent);
  box-shadow: var(--shadow), inset 0 0 0 1px var(--accent);
}

.level-card-head {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
}

.level-badge {
  flex: none;
  font-weight: 700;
  font-size: 0.85rem;
  letter-spacing: 0.04em;
  padding: 4px 10px;
  border-radius: 8px;
  background: var(--accent-soft);
  color: var(--accent);
}
.level-card.selected .level-badge {
  background: var(--accent);
  color: var(--accent-ink);
}

.level-name { font-weight: 600; font-size: 0.95rem; }
.level-total { margin-left: auto; font-size: 0.8rem; color: var(--ink-soft); white-space: nowrap; }

.level-card-stats {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-top: 10px;
  font-size: 0.78rem;
  color: var(--ink-soft);
}
.level-card-stats b { color: var(--ink); font-weight: 600; }
.level-pct { margin-left: auto; font-weight: 700; color: var(--accent); font-size: 0.9rem; }

/* Shows which level a setup or session screen belongs to */
.level-chip {
  flex: none;
  margin-left: auto;
  font-weight: 700;
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  padding: 4px 9px;
  border-radius: 8px;
  background: var(--accent-soft);
  color: var(--accent);
  min-width: 34px;
  text-align: center;
}

@media (max-width: 380px) {
  .level-card-stats { flex-wrap: wrap; gap: 8px; }
  .level-pct { margin-left: 0; }
}


/* Buttons */
.btn {
  border: none;
  border-radius: 12px;
  padding: 14px 20px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  transition: transform 0.05s ease, opacity 0.15s ease;
}
.btn:active { transform: scale(0.98); }
.btn:disabled { opacity: 0.4; cursor: not-allowed; }

.btn-primary { background: var(--accent); color: var(--accent-ink); }
.btn-primary:hover:not(:disabled) { opacity: 0.9; }

.btn-secondary { background: var(--surface); color: var(--ink); border: 1px solid var(--border); }
.btn-secondary:hover { background: var(--accent-soft); }

.btn-large { width: 100%; padding: 18px; font-size: 1.05rem; }
.btn-emoji { font-size: 1.2rem; }

.btn-link {
  background: none;
  border: none;
  color: var(--ink-soft);
  text-decoration: underline;
  font-size: 0.85rem;
  cursor: pointer;
  margin: 20px auto 0;
  padding: 8px;
}

.home-actions { display: flex; flex-direction: column; gap: 12px; margin-top: 28px; }

/* Setup screens */
.setup-group { margin-bottom: 24px; }
.setup-group h3 { font-size: 0.85rem; text-transform: uppercase; letter-spacing: 0.04em; color: var(--ink-soft); margin: 0 0 10px; }
.option-row { display: flex; gap: 10px; }
.option-btn {
  flex: 1;
  background: var(--surface);
  border: 1.5px solid var(--border);
  color: var(--ink);
  padding: 14px 10px;
  border-radius: 12px;
  font-size: 0.92rem;
  font-weight: 600;
  cursor: pointer;
}
.option-btn:hover { background: var(--accent-soft); }
.option-btn.selected { border-color: var(--accent); background: var(--accent-soft); color: var(--accent); }

#screen-study-setup, #screen-flash-setup { padding-top: 4px; }
#btn-start-study, #btn-start-flash { margin-top: 12px; }

/* Session header */
.session-header { display: flex; align-items: center; gap: 12px; margin: 8px 0 20px; }
.session-progress { flex: 1; }
.session-progress-bar { height: 6px; background: var(--border); border-radius: 4px; overflow: hidden; margin-bottom: 6px; }
.session-progress-fill { height: 100%; background: var(--accent); border-radius: 4px; transition: width 0.2s ease; }
.session-progress-text { font-size: 0.78rem; color: var(--ink-soft); text-align: center; }

/* Card */
.card-area { flex: 1; display: flex; align-items: center; justify-content: center; min-height: 220px; margin-bottom: 20px; }
.card {
  background: var(--surface);
  border: 3px solid var(--border);
  border-radius: 20px;
  box-shadow: var(--shadow);
  width: 100%;
  min-height: 220px;
  padding: 28px 24px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  position: relative;
  gap: 10px;
}
.card.card-clickable { cursor: pointer; }
/* Border color reflects how well the word was known last time it was rated
   (level 0 = neutral grey ... level 5 = green), same palette as the level bar. */
.card.card-level-0 { border-color: var(--l0); }
.card.card-level-1 { border-color: var(--l1); }
.card.card-level-2 { border-color: var(--l2); }
.card.card-level-3 { border-color: var(--l3); }
.card.card-level-4 { border-color: var(--l4); }
.card.card-level-5 { border-color: var(--l5); }
.card-type-badge {
  position: absolute;
  top: 14px;
  left: 16px;
  font-size: 0.7rem;
  color: var(--ink-soft);
  background: var(--bg);
  padding: 3px 9px;
  border-radius: 20px;
  border: 1px solid var(--border);
}
.card-front { font-size: 1.5rem; font-weight: 700; line-height: 1.3; }
.card-back { width: 100%; display: flex; flex-direction: column; align-items: center; gap: 8px; }
.card-divider { width: 60%; height: 1px; background: var(--border); margin: 6px 0; }
.card-back-text { font-size: 1.4rem; font-weight: 700; color: var(--accent); line-height: 1.3; }
.card-partizip { font-size: 0.85rem; color: var(--ink-soft); }

/* Answer area */
.answer-area { display: flex; flex-direction: column; gap: 10px; }
#answer-input {
  width: 100%;
  padding: 14px 16px;
  font-size: 1rem;
  border-radius: 12px;
  border: 1.5px solid var(--border);
  background: var(--surface);
  color: var(--ink);
}
#answer-input:focus { outline: none; border-color: var(--accent); }
.answer-feedback { min-height: 20px; font-size: 0.9rem; font-weight: 600; text-align: center; }
.answer-feedback.correct { color: var(--l5); }
.answer-feedback.incorrect { color: var(--accent); }
.answer-buttons { display: flex; gap: 10px; }
.answer-buttons .btn { flex: 1; }

/* Rating */
.rate-area { margin-top: 8px; }
.rate-label { text-align: center; color: var(--ink-soft); font-size: 0.88rem; margin: 0 0 12px; }
.rate-buttons { display: flex; gap: 8px; }
.rate-btn {
  flex: 1;
  border: none;
  border-radius: 12px;
  padding: 12px 4px;
  font-size: 1.1rem;
  font-weight: 700;
  color: #241f18;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}
.rate-btn span { font-size: 0.62rem; font-weight: 500; }
.rate-1 { background: var(--l1); }
.rate-2 { background: var(--l2); }
.rate-3 { background: var(--l3); }
.rate-4 { background: var(--l4); }
.rate-5 { background: var(--l5); color: #fff; }
.rate-btn:active { transform: scale(0.96); }

/* Browse nav */
.browse-area { display: flex; gap: 10px; margin-top: 8px; }
.browse-area .btn { flex: 1; }

/* Summary */
.summary-line { text-align: center; font-size: 1rem; margin: 0 0 16px; }

@media (max-width: 380px) {
  .card-front { font-size: 1.3rem; }
  .card-back-text { font-size: 1.2rem; }
}