/* ── Custom Properties ─────────────────────────────── */
:root {
  --color-primary: #1a56db;
  --color-primary-dark: #1240a4;
  --color-bg: #f3f4f6;
  --color-card: #ffffff;
  --color-text: #1f2937;
  --color-muted: #6b7280;
  --color-correct: #16a34a;
  --color-correct-bg: #dcfce7;
  --color-wrong: #dc2626;
  --color-wrong-bg: #fee2e2;
  --color-border: #e5e7eb;
  --radius: 10px;
  --shadow: 0 1px 3px rgba(0,0,0,.1);
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

/* ── Reset ────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body {
  font-family: var(--font);
  background: var(--color-bg);
  color: var(--color-text);
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
}

/* ── Header ───────────────────────────────────────── */
header {
  background: var(--color-primary);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px;
  position: sticky;
  top: 0;
  z-index: 10;
}
.logo { font-size: 1.15rem; font-weight: 700; }

.lang-toggle {
  display: flex;
  background: rgba(255,255,255,.2);
  border-radius: 20px;
  overflow: hidden;
}
.lang-btn {
  background: none;
  border: none;
  color: rgba(255,255,255,.7);
  font-weight: 600;
  font-size: .85rem;
  padding: 6px 14px;
  cursor: pointer;
  transition: background .2s, color .2s;
}
.lang-btn.active {
  background: #fff;
  color: var(--color-primary);
  border-radius: 20px;
}

/* ── Screens ──────────────────────────────────────── */
.screen { display: none; flex: 1; padding: 24px 16px; max-width: 600px; margin: 0 auto; width: 100%; }
.screen.active { display: flex; flex-direction: column; }

/* ── Start Screen ─────────────────────────────────── */
#start-screen { align-items: center; justify-content: center; gap: 24px; }
#start-screen h2 { font-size: 1.3rem; text-align: center; }
.mode-buttons { display: flex; flex-direction: column; gap: 12px; width: 100%; }
.mode-btn {
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: var(--radius);
  padding: 16px;
  font-size: 1.05rem;
  font-weight: 600;
  cursor: pointer;
  transition: background .2s;
  width: 100%;
}
.mode-btn:hover, .mode-btn:focus-visible { background: var(--color-primary-dark); }
.checkbox-label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: .95rem;
  color: var(--color-muted);
  cursor: pointer;
}
.checkbox-label input { width: 18px; height: 18px; accent-color: var(--color-primary); }

/* ── Quiz Screen ──────────────────────────────────── */
#quiz-screen { gap: 16px; }

/* Progress bar */
.progress-bar { text-align: center; }
.progress-bar span { font-size: .85rem; color: var(--color-muted); }
.progress-track { height: 6px; background: var(--color-border); border-radius: 3px; margin-top: 6px; overflow: hidden; }
.progress-fill { height: 100%; width: 0; background: var(--color-primary); border-radius: 3px; transition: width .3s; }

/* Score bar */
.score-bar { display: flex; justify-content: center; gap: 24px; font-size: .9rem; font-weight: 600; }
.score-correct { color: var(--color-correct); }
.score-wrong { color: var(--color-wrong); }

/* Question card */
.question-card {
  background: var(--color-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 14px;
}
.category-badge {
  font-size: .75rem;
  color: var(--color-muted);
  text-transform: uppercase;
  letter-spacing: .03em;
}
.question-text { font-size: 1.1rem; font-weight: 600; line-height: 1.45; }

/* Choices */
.choices { display: flex; flex-direction: column; gap: 10px; }
.choice-btn {
  background: var(--color-bg);
  border: 2px solid var(--color-border);
  border-radius: var(--radius);
  padding: 14px 16px;
  font-size: 1rem;
  text-align: left;
  cursor: pointer;
  transition: border-color .2s, background .2s;
  min-height: 48px;
  line-height: 1.35;
}
.choice-btn:hover:not(.disabled) { border-color: var(--color-primary); }
.choice-btn.correct {
  border-color: var(--color-correct);
  background: var(--color-correct-bg);
}
.choice-btn.wrong {
  border-color: var(--color-wrong);
  background: var(--color-wrong-bg);
}
.choice-btn.disabled { cursor: default; opacity: .85; }

/* Next button */
.btn-next {
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: var(--radius);
  padding: 14px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background .2s;
  width: 100%;
}
.btn-next:hover { background: var(--color-primary-dark); }

/* ── Results Screen ───────────────────────────────── */
#results-screen { align-items: center; gap: 20px; }
.result-banner {
  font-size: 1.8rem;
  font-weight: 800;
  padding: 16px 32px;
  border-radius: var(--radius);
  text-align: center;
  width: 100%;
}
.result-banner.pass { background: var(--color-correct-bg); color: var(--color-correct); }
.result-banner.fail { background: var(--color-wrong-bg); color: var(--color-wrong); }
.result-score { font-size: 1.15rem; color: var(--color-muted); }

.result-missed {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.result-missed h3 { font-size: 1rem; color: var(--color-wrong); }
.missed-item {
  background: var(--color-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 14px;
}
.missed-item .missed-q { font-weight: 600; margin-bottom: 6px; }
.missed-item .missed-your { color: var(--color-wrong); font-size: .9rem; }
.missed-item .missed-correct { color: var(--color-correct); font-size: .9rem; }

.result-actions { display: flex; flex-direction: column; gap: 10px; width: 100%; margin-top: 8px; }

/* ── Transition Screen ────────────────────────────── */
#transition-screen { align-items: center; justify-content: center; }
.transition-card {
  background: var(--color-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 32px 24px;
  text-align: center;
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-width: 440px;
}
.transition-card h2 { font-size: 1.4rem; color: var(--color-correct); }
.transition-card p { font-size: 1rem; color: var(--color-muted); line-height: 1.5; }

/* ── Stage Badge ─────────────────────────────────── */
.stage-badge {
  text-align: center;
  font-size: .8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--color-primary);
  padding: 4px 12px;
  background: rgba(26, 86, 219, .1);
  border-radius: 20px;
  align-self: center;
}

/* ── Oral Controls ───────────────────────────────── */
.oral-controls {
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.btn-listen {
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: var(--radius);
  padding: 10px 20px;
  font-size: .95rem;
  font-weight: 600;
  cursor: pointer;
  transition: background .2s;
  align-self: flex-start;
}
.btn-listen:hover { background: var(--color-primary-dark); }
.btn-listen.playing {
  background: var(--color-correct);
  pointer-events: none;
}

.oral-input-row {
  display: flex;
  gap: 8px;
  align-items: stretch;
}
.oral-text-input {
  flex: 1;
  padding: 12px 14px;
  font-size: 1rem;
  border: 2px solid var(--color-border);
  border-radius: var(--radius);
  font-family: var(--font);
  transition: border-color .2s;
}
.oral-text-input:focus {
  outline: none;
  border-color: var(--color-primary);
}

.btn-mic {
  width: 48px;
  min-height: 48px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-bg);
  font-size: 1.3rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: border-color .2s, background .2s;
}
.btn-mic.recording {
  border-color: var(--color-wrong);
  background: var(--color-wrong-bg);
  animation: mic-pulse 1.2s ease-in-out infinite;
}
@keyframes mic-pulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(220, 38, 38, .4); }
  50% { box-shadow: 0 0 0 8px rgba(220, 38, 38, 0); }
}

.stt-transcript {
  font-size: .85rem;
  color: var(--color-muted);
  font-style: italic;
  min-height: 1.2em;
}

.btn-submit-oral {
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: var(--radius);
  padding: 12px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background .2s;
}
.btn-submit-oral:hover { background: var(--color-primary-dark); }

.oral-feedback {
  padding: 12px;
  border-radius: var(--radius);
  font-size: .95rem;
  line-height: 1.45;
}
.oral-feedback.match-correct {
  background: var(--color-correct-bg);
  color: var(--color-correct);
  font-weight: 600;
}
.oral-feedback.match-wrong {
  background: var(--color-wrong-bg);
  color: var(--color-text);
}
.oral-feedback .accepted-label {
  font-weight: 600;
  color: var(--color-correct);
}

.self-grade-buttons {
  display: flex;
  gap: 10px;
}
.btn-self-grade {
  flex: 1;
  padding: 12px;
  border: none;
  border-radius: var(--radius);
  font-size: .95rem;
  font-weight: 600;
  cursor: pointer;
  transition: opacity .2s;
}
.btn-self-grade:hover { opacity: .85; }
.btn-self-grade.correct { background: var(--color-correct-bg); color: var(--color-correct); }
.btn-self-grade.wrong { background: var(--color-wrong-bg); color: var(--color-wrong); }

/* ── Utility ──────────────────────────────────────── */
.hidden { display: none !important; }

/* ── Tablet+ ──────────────────────────────────────── */
@media (min-width: 768px) {
  header { padding: 14px 32px; }
  .logo { font-size: 1.3rem; }
  .screen { padding: 32px 24px; }
  .mode-buttons { flex-direction: row; }
  .mode-btn { flex: 1; }
  .result-actions { flex-direction: row; }
  .result-actions .mode-btn { flex: 1; }
}