/* ══════════════════════════════════════════
   CSS VARIABLES — LIGHT THEME (default)
══════════════════════════════════════════ */
:root {
  --bg:           #f7f7f7;
  --surface:      #ffffff;
  --surface-2:    #f0f0f0;
  --surface-3:    #f5f5f5;
  --border:       #e5e5e5;
  --border-2:     #f0f0f0;

  --text-1:       #2c2c2c;
  --text-2:       #3c3c3c;
  --text-3:       #555555;
  --text-4:       #777777;
  --text-5:       #999999;
  --text-6:       #cccccc;

  --green-surface: #f0fce8;
  --green-border:  #c8f0a0;
  --green-text:    #3a8c00;

  --correct-bg:   #e8ffd4;
  --correct-text: #2d7a00;
  --wrong-bg:     #ffe4e4;
  --wrong-text:   #c03030;

  --streak-bg:     #fff4e0;
  --streak-border: #ffd080;
  --streak-text:   #b86e00;

  --badge-level-bg:     #e8f5e2;
  --badge-level-text:   #3a7a00;
  --badge-level-border: #b8e090;
  --badge-mode-bg:      #ede8f8;
  --badge-mode-text:    #5a3090;
  --badge-mode-border:  #c8b8f0;

  --shadow: 0 4px 20px rgba(0,0,0,0.08);
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.06);
}

/* ── DARK THEME ─────────────────────────── */
body.dark {
  --bg:           #0f172a;
  --surface:      #1e293b;
  --surface-2:    #334155;
  --surface-3:    #2d3f55;
  --border:       #334155;
  --border-2:     #2d3f55;

  --text-1:       #f1f5f9;
  --text-2:       #e2e8f0;
  --text-3:       #cbd5e1;
  --text-4:       #94a3b8;
  --text-5:       #64748b;
  --text-6:       #475569;

  --green-surface: #0a2010;
  --green-border:  #1a4a1a;
  --green-text:    #6ee46e;

  --correct-bg:   #0d2a0d;
  --correct-text: #6ee46e;
  --wrong-bg:     #2a0d0d;
  --wrong-text:   #ff8080;

  --streak-bg:     #1a1200;
  --streak-border: #4a3800;
  --streak-text:   #ffb030;

  --badge-level-bg:     #0a2010;
  --badge-level-text:   #6ee46e;
  --badge-level-border: #1a4a1a;
  --badge-mode-bg:      #1a0a2a;
  --badge-mode-text:    #b88af0;
  --badge-mode-border:  #3a1a5a;

  --shadow: 0 4px 20px rgba(0,0,0,0.35);
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.25);
}


/* ══════════════════════════════════════════
   RESET & BASE
══════════════════════════════════════════ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: 'Segoe UI', system-ui, sans-serif;
  background: var(--bg);
  color: var(--text-2);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  transition: background-color 0.3s, color 0.3s;
}

.hidden { display: none !important; }


/* ══════════════════════════════════════════
   SHARED TOPBAR
══════════════════════════════════════════ */
.topbar {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 4px;
  margin-bottom: 4px;
}

.topbar-logo {
  font-size: 1.3rem;
  font-weight: 900;
  color: #58CC02;
  letter-spacing: -0.5px;
}

.topbar-title {
  font-size: 1.1rem;
  font-weight: 800;
  color: var(--text-1);
}

.topbar-controls {
  display: flex;
  gap: 4px;
}

.icon-btn {
  background: var(--surface-2);
  border: none;
  border-radius: 10px;
  width: 34px;
  height: 34px;
  font-size: 1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s, transform 0.1s;
}
.icon-btn:hover  { background: var(--border); }
.icon-btn:active { transform: scale(0.93); }


/* ══════════════════════════════════════════
   SETUP SCREEN
══════════════════════════════════════════ */
#setupScreen {
  width: 100%;
  max-width: 480px;
  padding: 24px 24px 32px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 18px;
}

.setup-section { width: 100%; }

.setup-section-title {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-5);
  margin-bottom: 10px;
}

.option-group {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.option-btn {
  flex: 1;
  min-width: 90px;
  padding: 12px 10px;
  border-radius: 14px;
  border: 2px solid var(--border);
  background: var(--surface);
  color: var(--text-4);
  font-size: 0.88rem;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  text-align: center;
  transition: border-color 0.2s, background 0.2s, color 0.2s;
}
.option-btn:hover   { border-color: var(--text-5); background: var(--surface-3); }
.option-btn.selected {
  border-color: #58CC02;
  background: var(--green-surface);
  color: var(--green-text);
}

.start-btn {
  width: 100%;
  padding: 18px;
  font-size: 1.05rem;
  border-radius: 18px;
}

.stats-link {
  background: none;
  border: none;
  color: var(--text-4);
  font-size: 0.88rem;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  padding: 4px 8px;
  border-radius: 8px;
  transition: color 0.2s;
}
.stats-link:hover { color: var(--text-2); }


/* ══════════════════════════════════════════
   STREAK PILL
══════════════════════════════════════════ */
.streak-pill {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  background: var(--streak-bg);
  border: 2px solid var(--streak-border);
  border-radius: 20px;
  padding: 6px 14px;
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--streak-text);
  transition: background 0.3s, border-color 0.3s, color 0.3s;
}
.streak-pill.small { padding: 4px 10px; font-size: 0.8rem; }


/* ══════════════════════════════════════════
   STATS SCREEN
══════════════════════════════════════════ */
#statsScreen {
  width: 100%;
  max-width: 480px;
  padding: 24px 24px 32px;
  display: flex;
  flex-direction: column;
  gap: 0;
}

.stats-body {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-top: 16px;
}

.stats-section-title {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-5);
  margin-bottom: -4px;
}

.stats-tiles-row {
  display: flex;
  gap: 12px;
}

.stats-tile {
  flex: 1;
  background: var(--surface);
  border: 2px solid var(--border);
  border-radius: 18px;
  padding: 18px 12px;
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: background 0.3s, border-color 0.3s;
}

.stats-tile-icon  { font-size: 1.8rem; margin-bottom: 6px; }
.stats-tile-value { font-size: 1.5rem; font-weight: 900; color: var(--text-1); line-height: 1; }
.stats-tile-label { font-size: 0.75rem; color: var(--text-5); margin-top: 4px; }

.stats-level-item {
  background: var(--surface);
  border: 2px solid var(--border);
  border-radius: 14px;
  padding: 14px 16px;
  box-shadow: var(--shadow-sm);
  transition: background 0.3s, border-color 0.3s;
}

.stats-level-meta {
  display: flex;
  justify-content: space-between;
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-2);
  margin-bottom: 8px;
}

.stats-bar-track {
  height: 8px;
  background: var(--border);
  border-radius: 20px;
  overflow: hidden;
}

.stats-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, #58CC02, #89e219);
  border-radius: 20px;
  width: 0%;
  transition: width 0.5s ease;
}


/* ══════════════════════════════════════════
   GAME SCREEN — HEADER
══════════════════════════════════════════ */
#gameScreen {
  width: 100%;
  max-width: 480px;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding-bottom: 32px;
}

header {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 24px 0;
}

.logo {
  font-size: 1.15rem;
  font-weight: 800;
  color: #58CC02;
}

.header-right {
  display: flex;
  align-items: center;
  gap: 6px;
}

.back-btn {
  background: none;
  border: 2px solid var(--border);
  border-radius: 12px;
  padding: 6px 12px;
  font-size: 0.82rem;
  color: var(--text-4);
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  transition: border-color 0.2s, color 0.2s;
}
.back-btn:hover { border-color: var(--text-4); color: var(--text-2); }


/* ══════════════════════════════════════════
   SESSION BADGES
══════════════════════════════════════════ */
.session-badges {
  display: flex;
  gap: 8px;
  margin-top: 14px;
  width: 100%;
  padding: 0 24px;
}

.badge {
  padding: 4px 12px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 700;
  transition: background 0.3s, color 0.3s, border-color 0.3s;
}
.level-badge {
  background: var(--badge-level-bg);
  color: var(--badge-level-text);
  border: 1px solid var(--badge-level-border);
}
.mode-badge {
  background: var(--badge-mode-bg);
  color: var(--badge-mode-text);
  border: 1px solid var(--badge-mode-border);
}


/* ══════════════════════════════════════════
   PROGRESS BAR
══════════════════════════════════════════ */
.progress-section {
  width: 100%;
  padding: 16px 24px 0;
}

.progress-labels {
  display: flex;
  justify-content: space-between;
  font-size: 0.8rem;
  color: var(--text-4);
  margin-bottom: 8px;
}

.progress-bar-track {
  width: 100%;
  height: 12px;
  background: var(--border);
  border-radius: 20px;
  overflow: hidden;
  transition: background 0.3s;
}

.progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, #58CC02, #89e219);
  border-radius: 20px;
  width: 0%;
  transition: width 0.4s ease;
}

.stats {
  display: flex;
  gap: 16px;
  margin-top: 8px;
  font-size: 0.8rem;
  font-weight: 600;
}
.stat.green { color: #58CC02; }
.stat.red   { color: #ff4b4b; }


/* ══════════════════════════════════════════
   FLASHCARD MODE
══════════════════════════════════════════ */
.card-container {
  perspective: 1200px;
  margin: 22px auto 0;
  width: 100%;
  max-width: 420px;
  padding: 0 24px;
}

.card {
  width: 100%;
  height: 300px;
  cursor: pointer;
}

.card-inner {
  width: 100%;
  height: 100%;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.55s cubic-bezier(0.4, 0.2, 0.2, 1);
}
.card-inner.flipped { transform: rotateY(180deg); }

.card-front,
.card-back {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  border-radius: 24px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 28px;
  box-shadow: var(--shadow);
  transition: background 0.3s, border-color 0.3s;
}

.card-front {
  background: var(--surface);
  border: 2px solid var(--border-2);
}

.card-back {
  background: var(--green-surface);
  border: 2px solid var(--green-border);
  transform: rotateY(180deg);
}

.action-buttons {
  display: flex;
  gap: 14px;
  margin: 20px auto 0;
  max-width: 420px;
  width: 100%;
  padding: 0 24px;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s;
}
.action-buttons.visible { opacity: 1; pointer-events: all; }


/* ══════════════════════════════════════════
   SHARED CARD ELEMENTS
══════════════════════════════════════════ */
.card-emoji        { font-size: 3rem; line-height: 1; }
.card-word         { font-size: 1.85rem; font-weight: 800; color: var(--text-1); text-align: center; }
.card-translation  { font-size: 1.65rem; font-weight: 800; color: var(--green-text); text-align: center; transition: color 0.3s; }
.card-example      { font-size: 0.9rem; color: var(--text-3); font-style: italic; text-align: center; line-height: 1.5; }
.flip-hint         { font-size: 0.7rem; color: var(--text-6); position: absolute; bottom: 14px; transition: color 0.3s; }

.speak-btn {
  background: var(--surface-2);
  border: none;
  border-radius: 14px;
  padding: 7px 16px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-3);
  cursor: pointer;
  font-family: inherit;
  transition: background 0.2s, transform 0.1s;
}
.speak-btn:hover  { background: var(--border); }
.speak-btn:active { transform: scale(0.96); }


/* ══════════════════════════════════════════
   STATIC CARD (quiz & writing)
══════════════════════════════════════════ */
.static-card {
  background: var(--surface);
  border: 2px solid var(--border-2);
  border-radius: 24px;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 28px;
  margin: 22px 24px 0;
  position: relative;
  transition: background 0.3s, border-color 0.3s;
}


/* ══════════════════════════════════════════
   QUIZ MODE
══════════════════════════════════════════ */
.quiz-options {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin: 14px 24px 0;
}

.quiz-option-btn {
  padding: 14px 10px;
  border-radius: 14px;
  border: 2px solid var(--border);
  background: var(--surface);
  color: var(--text-2);
  font-size: 0.9rem;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  text-align: center;
  word-break: break-word;
  line-height: 1.3;
  transition: background 0.15s, border-color 0.15s, transform 0.1s, color 0.15s;
}
.quiz-option-btn:hover:not(:disabled)  { background: var(--surface-3); border-color: var(--text-5); }
.quiz-option-btn:active:not(:disabled) { transform: scale(0.97); }
.quiz-option-btn:disabled { cursor: default; }
.quiz-option-btn.correct  { background: var(--correct-bg); border-color: #58CC02;  color: var(--correct-text); }
.quiz-option-btn.wrong    { background: var(--wrong-bg);   border-color: #ff4b4b;  color: var(--wrong-text); }

.quiz-score-bar {
  text-align: center;
  margin-top: 14px;
  font-size: 0.88rem;
  color: var(--text-4);
}
.quiz-score-bar strong { color: var(--text-1); }


/* ══════════════════════════════════════════
   WRITING MODE
══════════════════════════════════════════ */
.writing-input-area {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin: 14px 24px 0;
  width: calc(100% - 48px);
}

#writeInput {
  width: 100%;
  padding: 14px 16px;
  border: 2px solid var(--border);
  border-radius: 14px;
  font-size: 1rem;
  font-family: inherit;
  color: var(--text-1);
  background: var(--surface);
  outline: none;
  transition: border-color 0.2s, background 0.3s, color 0.3s;
}
#writeInput::placeholder { color: var(--text-5); }
#writeInput:focus    { border-color: #8549BA; }
#writeInput:disabled { background: var(--surface-3); color: var(--text-4); }

.writing-feedback {
  margin: 10px 24px 0;
  padding: 12px 16px;
  border-radius: 14px;
  font-size: 0.92rem;
  font-weight: 600;
  min-height: 44px;
  text-align: center;
  transition: background 0.2s, color 0.2s;
}
.writing-feedback.correct { background: var(--correct-bg); color: var(--correct-text); }
.writing-feedback.wrong   { background: var(--wrong-bg);   color: var(--wrong-text); }

.next-container {
  margin: 12px 24px 0;
  width: calc(100% - 48px);
}
.next-container .btn { width: 100%; }


/* ══════════════════════════════════════════
   SHARED BUTTONS
══════════════════════════════════════════ */
.btn {
  padding: 15px;
  border: none;
  border-radius: 16px;
  font-size: 1rem;
  font-weight: 700;
  font-family: inherit;
  cursor: pointer;
  transition: transform 0.15s, box-shadow 0.15s, background 0.15s;
}
.btn:active { transform: scale(0.97); }

.btn-correct {
  background: #58CC02;
  color: white;
  box-shadow: 0 4px 0 #3e9100;
}
.btn-correct:hover  { background: #50b800; }
.btn-correct:active { box-shadow: none; transform: translateY(2px); }

.btn-wrong {
  background: #ff4b4b;
  color: white;
  box-shadow: 0 4px 0 #c03030;
}
.btn-wrong:hover  { background: #e84040; }
.btn-wrong:active { box-shadow: none; transform: translateY(2px); }

.btn-primary {
  background: #8549BA;
  color: white;
  box-shadow: 0 4px 0 #5c2f8a;
}
.btn-primary:hover   { background: #7540aa; }
.btn-primary:active  { box-shadow: none; transform: translateY(2px); }
.btn-primary:disabled { background: var(--surface-2); color: var(--text-5); box-shadow: none; cursor: default; }

.btn-outline {
  background: transparent;
  border: 2px solid var(--border);
  color: var(--text-4);
  box-shadow: none;
  margin-top: 8px;
  transition: border-color 0.2s, color 0.2s;
}
.btn-outline:hover { border-color: var(--text-4); color: var(--text-2); }


/* ══════════════════════════════════════════
   BOTTOM ACTIONS
══════════════════════════════════════════ */
.bottom-actions { margin-top: 22px; }

.reset-btn {
  background: none;
  border: 2px solid var(--border);
  border-radius: 12px;
  padding: 7px 16px;
  font-size: 0.8rem;
  color: var(--text-5);
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  transition: border-color 0.2s, color 0.2s;
}
.reset-btn:hover { border-color: #ff4b4b; color: #ff4b4b; }


/* ══════════════════════════════════════════
   COMPLETION SCREEN
══════════════════════════════════════════ */
.completion-screen {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: 100;
  align-items: center;
  justify-content: center;
}
.completion-screen.visible { display: flex; }

.completion-content {
  background: var(--surface);
  border-radius: 28px;
  padding: 40px 28px;
  text-align: center;
  max-width: 340px;
  width: 90%;
  box-shadow: 0 20px 60px rgba(0,0,0,0.3);
  display: flex;
  flex-direction: column;
  transition: background 0.3s;
}
.completion-emoji      { font-size: 3.5rem; margin-bottom: 12px; }
.completion-content h2 { font-size: 1.3rem; font-weight: 800; color: var(--text-1); margin-bottom: 6px; }
.completion-content p  { color: var(--text-4); font-size: 0.9rem; margin-bottom: 20px; }


/* ══════════════════════════════════════════
   RESPONSIVE
══════════════════════════════════════════ */
@media (max-width: 400px) {
  .card { height: 270px; }
  .card-word { font-size: 1.55rem; }
  .card-translation { font-size: 1.4rem; }
  .card-emoji { font-size: 2.6rem; }
  .quiz-options { grid-template-columns: 1fr; }
}