* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
  background: #f0f4f8;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  padding: 20px;
}

.container {
  background: #ffffff;
  padding: 25px;
  border-radius: 16px;
  box-shadow: 0 10px 25px rgba(0,0,0,0.08);
  text-align: center;
  max-width: 400px;
  width: 100%;
}

h1 {
  color: #2c3e50;
  margin-bottom: 5px;
}

.subtitle {
  color: #7f8c8d;
  font-size: 0.9rem;
  margin-bottom: 15px;
}

.score-board {
  display: flex;
  justify-content: space-around;
  margin-bottom: 20px;
  font-size: 1.05rem;
  color: #34495e;
}

.game-board {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin-bottom: 20px;
}

.card {
  height: 75px;
  background: #3498db;
  border-radius: 10px;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 2rem;
  cursor: pointer;
  user-select: none;
  transition: transform 0.3s ease, background-color 0.3s;
}

.card.flipped {
  background: #ffffff;
  border: 2px solid #3498db;
  transform: rotateY(180deg);
}

.card.matched {
  background: #2ecc71;
  border: none;
  cursor: default;
}

#restart-btn {
  background: #3498db;
  color: white;
  border: none;
  padding: 10px 20px;
  font-size: 1rem;
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.2s;
}

#restart-btn:hover {
  background: #2980b9;
}