/* ============================================================
   RESET & VARIABILI CSS
   Definisce i colori e valori riutilizzabili in tutto il file
============================================================ */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  /* Colori tema scuro */
  --bg-primary:    #0f1117;
  --bg-secondary:  #1a1d27;
  --bg-card:       #20253a;
  --bg-card-hover: #252b42;
  --border:        #2e3450;

  /* Colori testo */
  --text-primary:  #e8ecf4;
  --text-secondary:#8b96b8;
  --text-muted:    #5a6380;

  /* Colori accento */
  --accent:        #4f8ef7;
  --accent-dark:   #3a72d8;
  --accent-glow:   rgba(79, 142, 247, 0.15);

  /* Colori feedback */
  --correct:       #22c55e;
  --correct-bg:    rgba(34, 197, 94, 0.12);
  --wrong:         #ef4444;
  --wrong-bg:      rgba(239, 68, 68, 0.12);
  --warning:       #f59e0b;

  /* Tipografia e layout */
  --radius:        12px;
  --radius-sm:     8px;
  --shadow:        0 4px 24px rgba(0,0,0,0.4);
  --transition:    0.2s ease;
  --max-width:     680px;
}

/* ============================================================
   BASE
============================================================ */
html { font-size: 16px; }

body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  line-height: 1.6;
  min-height: 100vh;
  /* Gradient sottile sullo sfondo */
  background-image: radial-gradient(ellipse at 20% 0%, rgba(79,142,247,0.06) 0%, transparent 60%);
}

/* ============================================================
   LAYOUT SCHERMATE
   Ogni "screen" è una pagina. Solo quella con .active è visibile.
============================================================ */
.screen {
  display: none;
  padding: 24px 16px 48px;
  animation: fadeIn 0.3s ease;
}
.screen.active { display: block; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
}

/* ============================================================
   CARD - Blocco contenuto riutilizzabile
============================================================ */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 16px;
  box-shadow: var(--shadow);
}

.card h2 {
  font-size: 0.85rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-secondary);
  margin-bottom: 16px;
}

/* ============================================================
   SCHERMATA HOME
============================================================ */
.home-header {
  text-align: center;
  padding: 32px 0 24px;
}
.drone-icon { font-size: 3rem; margin-bottom: 12px; }
.home-header h1 {
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 6px;
}
.subtitle {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

/* Bottoni modalità (Allenamento / Esame) */
.mode-buttons {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}
.mode-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  padding: 20px 12px;
  background: var(--bg-secondary);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  color: var(--text-primary);
  transition: var(--transition);
}
.mode-btn:hover { border-color: var(--accent); background: var(--bg-card-hover); }
.mode-btn.active { border-color: var(--accent); background: var(--accent-glow); }
.mode-btn .mode-icon { font-size: 1.8rem; }
.mode-btn strong { font-size: 0.95rem; }
.mode-btn small { color: var(--text-secondary); font-size: 0.78rem; text-align: center; }

/* Bottoni numero domande */
.count-buttons {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}
.count-btn {
  flex: 1;
  min-width: 60px;
  padding: 12px 8px;
  background: var(--bg-secondary);
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  color: var(--text-primary);
  font-size: 1rem;
  font-weight: 600;
  transition: var(--transition);
}
.count-btn:hover { border-color: var(--accent); }
.count-btn.active { border-color: var(--accent); background: var(--accent-glow); color: var(--accent); }

/* Griglia categorie */
.category-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.cat-chip {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 20px;
  cursor: pointer;
  font-size: 0.85rem;
  transition: var(--transition);
  user-select: none;
}
.cat-chip input[type="checkbox"] { display: none; }
.cat-chip:has(input:checked) {
  border-color: var(--accent);
  background: var(--accent-glow);
  color: var(--accent);
}
.cat-chip:hover { border-color: var(--accent); }

/* Sezione statistiche */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-bottom: 16px;
}
.stat-item {
  text-align: center;
  background: var(--bg-secondary);
  border-radius: var(--radius-sm);
  padding: 12px 8px;
}
.stat-value {
  display: block;
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--accent);
}
.stat-label {
  display: block;
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-top: 4px;
}

/* Pulsante avvio principale */
.btn-start {
  width: 100%;
  margin-top: 8px;
  font-size: 1.1rem;
  padding: 16px;
}

/* ============================================================
   BOTTONI GENERICI
============================================================ */
.btn-primary {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  padding: 12px 24px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  text-align: center;
}
.btn-primary:hover { background: var(--accent-dark); transform: translateY(-1px); }
.btn-primary:active { transform: translateY(0); }

.btn-secondary {
  display: inline-block;
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--accent);
  border-radius: var(--radius-sm);
  padding: 10px 20px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}
.btn-secondary:hover { background: var(--accent-glow); }

.btn-danger-small {
  background: transparent;
  color: var(--wrong);
  border: 1px solid var(--wrong);
  border-radius: var(--radius-sm);
  padding: 8px 16px;
  font-size: 0.8rem;
  cursor: pointer;
  transition: var(--transition);
}
.btn-danger-small:hover { background: var(--wrong-bg); }

/* ============================================================
   SCHERMATA QUIZ
============================================================ */
.quiz-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 12px;
}
.btn-back {
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  border-radius: var(--radius-sm);
  width: 36px;
  height: 36px;
  font-size: 1rem;
  cursor: pointer;
  flex-shrink: 0;
  transition: var(--transition);
}
.btn-back:hover { color: var(--wrong); border-color: var(--wrong); }

.progress-info {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.progress-info span { font-size: 0.85rem; color: var(--text-secondary); }
.score-live { color: var(--accent) !important; font-weight: 600; }

.category-badge {
  font-size: 0.72rem;
  padding: 4px 10px;
  border-radius: 12px;
  background: var(--accent-glow);
  color: var(--accent);
  border: 1px solid rgba(79,142,247,0.3);
  white-space: nowrap;
}

/* Barra di avanzamento */
.progress-bar-wrap {
  height: 4px;
  background: var(--border);
  border-radius: 2px;
  margin-bottom: 20px;
  overflow: hidden;
}
.progress-bar {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), #7bb5ff);
  border-radius: 2px;
  transition: width 0.4s ease;
}

/* Card domanda */
.question-card {
  margin-bottom: 16px;
}
.question-text {
  font-size: 1.05rem;
  line-height: 1.65;
  color: var(--text-primary);
  font-weight: 500;
}

/* Opzioni risposta */
.options-container {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 16px;
}
.option-btn {
  width: 100%;
  text-align: left;
  padding: 14px 18px;
  background: var(--bg-card);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  color: var(--text-primary);
  font-size: 0.95rem;
  line-height: 1.5;
  transition: var(--transition);
  display: flex;
  align-items: flex-start;
  gap: 12px;
}
.option-btn:hover:not(:disabled) {
  border-color: var(--accent);
  background: var(--accent-glow);
}
.option-letter {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  font-size: 0.78rem;
  font-weight: 700;
  flex-shrink: 0;
  margin-top: 1px;
  transition: var(--transition);
}
.option-btn:hover:not(:disabled) .option-letter {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

/* Stili dopo la risposta */
.option-btn.correct {
  border-color: var(--correct);
  background: var(--correct-bg);
}
.option-btn.correct .option-letter { background: var(--correct); color: #fff; border-color: var(--correct); }

.option-btn.wrong {
  border-color: var(--wrong);
  background: var(--wrong-bg);
}
.option-btn.wrong .option-letter { background: var(--wrong); color: #fff; border-color: var(--wrong); }

.option-btn:disabled { cursor: not-allowed; }

/* Feedback (modalità allenamento) */
.feedback-box {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 16px;
  animation: fadeIn 0.3s ease;
}
.feedback-box.is-correct { border-color: var(--correct); background: var(--correct-bg); }
.feedback-box.is-wrong { border-color: var(--wrong); background: var(--wrong-bg); }

.feedback-icon { font-size: 1.8rem; margin-bottom: 8px; }
.feedback-text {
  font-weight: 700;
  font-size: 1rem;
  margin-bottom: 8px;
}
.feedback-spiegazione {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 16px;
}
#btn-next { width: 100%; }

.btn-next-exam {
  width: 100%;
  margin-top: 4px;
}

/* ============================================================
   SCHERMATA RISULTATI
============================================================ */
.result-card {
  text-align: center;
  padding: 32px 24px;
  margin-bottom: 24px;
}
.result-emoji { font-size: 3.5rem; margin-bottom: 12px; }
.result-card h2 { font-size: 1.4rem; margin-bottom: 16px; color: var(--text-secondary); font-weight: 400; text-transform: none; letter-spacing: 0; }

.result-score {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  margin-bottom: 16px;
}
.result-percent {
  font-size: 3.5rem;
  font-weight: 800;
  line-height: 1;
}
.result-fraction { color: var(--text-secondary); font-size: 1rem; }

.result-bar-wrap {
  height: 8px;
  background: var(--border);
  border-radius: 4px;
  margin: 0 auto 16px;
  max-width: 300px;
  overflow: hidden;
}
.result-bar {
  height: 100%;
  border-radius: 4px;
  transition: width 1s ease;
}
.result-message { color: var(--text-secondary); font-size: 0.9rem; }

/* Colori risultato */
.result-great .result-percent { color: var(--correct); }
.result-great .result-bar { background: var(--correct); }
.result-ok .result-percent { color: var(--warning); }
.result-ok .result-bar { background: var(--warning); }
.result-bad .result-percent { color: var(--wrong); }
.result-bad .result-bar { background: var(--wrong); }

/* Riepilogo risposte */
.review-title {
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: 12px;
  font-weight: 600;
}
.review-item {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px 16px;
  margin-bottom: 10px;
  font-size: 0.88rem;
}
.review-item.correct { border-left: 3px solid var(--correct); }
.review-item.wrong   { border-left: 3px solid var(--wrong); }

.review-item .review-q {
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 6px;
  line-height: 1.4;
}
.review-item .review-answers { color: var(--text-secondary); line-height: 1.6; }
.review-item .review-answers .user-ans { color: var(--wrong); }
.review-item .review-answers .correct-ans { color: var(--correct); }
.review-item .review-spieg {
  margin-top: 8px;
  padding-top: 8px;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 0.82rem;
  line-height: 1.5;
}

.result-buttons {
  display: flex;
  gap: 12px;
  margin-top: 24px;
}
.result-buttons .btn-primary,
.result-buttons .btn-secondary { flex: 1; text-align: center; }

/* ============================================================
   RESPONSIVE – schermi piccoli (telefono)
============================================================ */
@media (max-width: 480px) {
  .mode-buttons { grid-template-columns: 1fr; }
  .stats-grid { grid-template-columns: repeat(3, 1fr); }
  .home-header h1 { font-size: 1.4rem; }
  .result-percent { font-size: 2.8rem; }
  .result-buttons { flex-direction: column; }
  .question-text { font-size: 0.98rem; }
  .option-btn { font-size: 0.9rem; padding: 12px 14px; }
  .card { padding: 18px; }
}