.game-header {
  text-align: center;
  padding: 1rem;
}

.game-header h1 {
  margin: 0.5rem 0;
  font-size: clamp(1.6rem, 4vw, 2.4rem);
  color: var(--primary-dark);
}

.controls {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  margin: 0.75rem 0;
}

.controls label {
  font-weight: 600;
  color: var(--text-soft);
}

.controls select {
  font: inherit;
  padding: 0.4rem 0.6rem;
  border-radius: 12px;
  border: 2px solid var(--primary);
  background: white;
  color: var(--text);
}

.btn-primary {
  font: inherit;
  font-weight: 700;
  padding: 0.55rem 1.2rem;
  border-radius: 999px;
  border: none;
  background: linear-gradient(90deg, var(--primary), var(--accent));
  color: white;
  cursor: pointer;
  box-shadow: var(--shadow);
  transition: transform 0.15s ease;
}
.btn-primary:hover { transform: translateY(-2px); }

.stats {
  display: flex;
  gap: 2rem;
  justify-content: center;
  font-size: 1.1rem;
  color: var(--text-soft);
  margin-top: 0.5rem;
}

.board {
  display: grid;
  gap: 0.75rem;
  max-width: 700px;
  margin: 1rem auto 3rem;
  padding: 0 1rem;
  perspective: 1000px;
}

.card {
  aspect-ratio: 3 / 4;
  position: relative;
  cursor: pointer;
  transform-style: preserve-3d;
  transition: transform 0.4s ease;
  border: none;
  background: transparent;
  padding: 0;
}

.card.flipped, .card.matched { transform: rotateY(180deg); }

.card-face {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 16px;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  font-size: clamp(2rem, 8vw, 3.5rem);
  box-shadow: var(--shadow);
  user-select: none;
}

.card-back {
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: white;
  font-weight: 800;
}

.card-front {
  background: white;
  transform: rotateY(180deg);
}

.card.matched .card-front {
  background: linear-gradient(135deg, #d1f5d3, #b3ebbf);
  animation: pop 0.4s ease;
}

@keyframes pop {
  0% { transform: rotateY(180deg) scale(1); }
  50% { transform: rotateY(180deg) scale(1.08); }
  100% { transform: rotateY(180deg) scale(1); }
}

.overlay {
  position: fixed;
  inset: 0;
  background: rgba(31, 27, 46, 0.55);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 10;
}

.overlay.hidden { display: none; }

.overlay-card {
  background: white;
  border-radius: var(--radius);
  padding: 2rem 3rem;
  text-align: center;
  box-shadow: var(--shadow);
  max-width: 90vw;
}

.overlay-card h2 {
  margin: 0 0 1rem;
  color: var(--primary-dark);
}