* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  min-height: 100vh;
  color: white;
  text-align: center;
  padding: 20px;
}

h1 {
  font-size: 2.2rem;
  margin-bottom: 15px;
}

#stats {
  margin-bottom: 20px;
  font-size: 1rem;
}

.board-wrapper {
  display: flex;
  justify-content: center;
  width: 100%;
}

.game-board {
  display: grid;
  gap: 12px;
  margin: 20px auto;
  max-width: 90vw;
}

.card {
  aspect-ratio: 1;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: black;
  border-radius: 9px;
  cursor: pointer;
  height: 60px;
  width: 60px;
  display: flex;
  align-items: center;
  justify-content: center;

  font-size: clamp(1.9rem, 2vw, 2.2rem);
  font-weight: bold;

  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.25);
  transition: transform 0.3s ease;
  transform-style: preserve-3d;
}

.card:not(.flipped):hover {
  transform: scale(1.06);
}

.game-board {
  perspective: 1000px;
}

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

.card.matched {
  opacity: 0.6;
  cursor: default;
  pointer-events: none;
}

.controls {
  margin-top: 15px;
  display: flex;
  gap: 10px;
  justify-content: center;
}

button {
  padding: 12px 22px;
  border-radius: 10px;
  border: none;
  background: white;
  color: #667eea;
  font-size: 1rem;
  font-weight: bold;
  cursor: pointer;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.25);
  transition: transform 0.2s ease;
}

button:hover {
  transform: translateY(-2px);
}

/* Responsive Design */
/* 📱 Mobile */
@media (max-width: 599px) {
  .game-board {
    grid-template-columns: repeat(4, 1fr);
    max-width: 300px;
    gap: 12px;
  }

  h1 {
    font-size: 1.8rem;
  }

  .card {
    font-size: 1.8rem;
  }
}

/* 📱 Tablet */
@media (min-width: 600px) and (max-width: 1023px) {
  .game-board {
    grid-template-columns: repeat(4, 1fr);
    max-width: 420px;
    gap: 14px;
  }

  .card {
    font-size: 2rem;
  }
}

/* 💻 Laptop & Desktop */
@media (min-width: 1024px) {
  .game-board {
    grid-template-columns: repeat(4, 1fr);
    max-width: 520px;
    gap: 16px;
  }
}