/* ============================================================
   exercises.css — Estils del sistema d'exercicis i gamificació
   ============================================================ */

/* ---------- Filtres d'exercicis ---------- */
.exercise-filters {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
  align-items: center;
}

.filter-chip {
  padding: 0.35rem 0.9rem;
  border-radius: 20px;
  border: 1px solid var(--color-border);
  background: var(--color-card);
  color: var(--color-text-muted);
  cursor: pointer;
  font-size: 0.82rem;
  font-weight: 500;
  transition: all var(--transition);
  font-family: var(--font-sans);
}

.filter-chip:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.filter-chip.active {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: white;
}

/* ---------- Targeta d'exercici ---------- */
.exercise-card {
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  margin-bottom: 1rem;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}

.exercise-card::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 4px;
  background: var(--color-border);
  transition: background var(--transition);
}

.exercise-card.difficulty-facil::before   { background: var(--color-success); }
.exercise-card.difficulty-mitja::before   { background: var(--color-warning); }
.exercise-card.difficulty-difícil::before { background: var(--color-danger); }

.exercise-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

.exercise-card.answered {
  opacity: 0.85;
}

.exercise-card.answered.correct {
  border-color: var(--color-success);
}

.exercise-card.answered.incorrect {
  border-color: var(--color-danger);
}

/* Capçalera de l'exercici */
.exercise-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: 1rem;
  gap: 1rem;
}

.exercise-meta {
  display: flex;
  gap: 0.4rem;
  flex-wrap: wrap;
  align-items: center;
}

.exercise-points {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--color-accent);
  display: flex;
  align-items: center;
  gap: 0.2rem;
}

/* Pregunta */
.exercise-question {
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.5;
  margin-bottom: 1.2rem;
  color: var(--color-text);
}

/* Opcions de test */
.exercise-options {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.option-btn {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  background: var(--color-bg);
  border: 2px solid var(--color-border);
  border-radius: var(--radius);
  cursor: pointer;
  font-size: 0.9rem;
  color: var(--color-text);
  text-align: left;
  transition: all var(--transition);
  font-family: var(--font-sans);
  width: 100%;
}

.option-btn:hover:not(:disabled) {
  border-color: var(--color-primary);
  background: rgba(26, 115, 232, 0.08);
}

.option-btn:disabled {
  cursor: default;
}

.option-btn.selected {
  border-color: var(--color-primary);
  background: rgba(26, 115, 232, 0.12);
}

.option-btn.correct {
  border-color: var(--color-success);
  background: rgba(67, 160, 71, 0.12);
  color: #4ade80;
}

.option-btn.incorrect {
  border-color: var(--color-danger);
  background: rgba(229, 57, 53, 0.1);
  color: #f87171;
}

.option-letter {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--color-border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: 700;
  flex-shrink: 0;
  transition: background var(--transition);
}

.option-btn.correct .option-letter  { background: var(--color-success); }
.option-btn.incorrect .option-letter { background: var(--color-danger); }

/* Explicació de la resposta */
.exercise-explanation {
  display: none;
  margin-top: 1rem;
  padding: 0.9rem 1rem;
  border-radius: var(--radius);
  font-size: 0.88rem;
  line-height: 1.6;
  border-left: 4px solid;
  animation: fadeIn 0.3s ease;
}

.exercise-explanation.show { display: block; }

.exercise-explanation.correct {
  background: rgba(67, 160, 71, 0.1);
  border-color: var(--color-success);
  color: #d4edda;
}

.exercise-explanation.incorrect {
  background: rgba(229, 57, 53, 0.08);
  border-color: var(--color-danger);
  color: #f8d7da;
}

/* ---------- Panell de puntuació / gamificació ---------- */
.score-panel {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.score-card {
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.2rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.score-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
}

.score-card.total::before    { background: var(--color-primary); }
.score-card.correct::before  { background: var(--color-success); }
.score-card.incorrect::before{ background: var(--color-danger); }
.score-card.streak::before   { background: var(--color-warning); }

.score-value {
  font-size: 2rem;
  font-weight: 800;
  color: var(--color-accent);
  font-family: var(--font-mono);
}

.score-label {
  font-size: 0.75rem;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.8px;
  margin-top: 0.3rem;
}

/* Barra de progrés d'exercicis */
.exercises-progress-bar {
  height: 10px;
  background: var(--color-card);
  border-radius: 5px;
  overflow: hidden;
  margin-bottom: 1.5rem;
  border: 1px solid var(--color-border);
}

.exercises-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--color-success), var(--color-accent));
  border-radius: 5px;
  transition: width 0.6s ease;
}

/* Celebració / confetti */
.celebration {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 99998;
  display: flex;
  align-items: center;
  justify-content: center;
}

.celebration-text {
  font-size: 3rem;
  font-weight: 900;
  color: var(--color-warning);
  text-shadow: 0 0 30px rgba(251, 140, 0, 0.8);
  animation: bounceIn 0.5s ease, fadeOut 0.5s ease 1.5s forwards;
}

@keyframes bounceIn {
  0%   { transform: scale(0); }
  60%  { transform: scale(1.2); }
  100% { transform: scale(1); }
}

@keyframes fadeOut {
  to { opacity: 0; transform: scale(1.5); }
}

/* Racxa (streak) indicador */
.streak-indicator {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--color-warning);
  padding: 0.2rem 0.6rem;
  background: rgba(251, 140, 0, 0.15);
  border-radius: 20px;
  border: 1px solid rgba(251, 140, 0, 0.3);
}

/* ---------- Botons de reset/control d'exercicis ---------- */
.exercises-actions {
  display: flex;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}