body {
  font-family: Arial, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
  background-color: #f0f0f0;
}

.game-container {
  text-align: center;
}

.grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  margin-top: 20px;
}

.card {
  background-color: #000000;
  width: 100px;
  height: 100px;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 24px;
  font-weight: bold;
  cursor: pointer;
  border-radius: 5px;
  user-select: none;
}

.card.flipped {
  background-color: #fff;
  pointer-events: none;
}

.card.matched {
  background-color: #d0f0c0;
  pointer-events: none;
}

.modal {
  display: none;
  position: fixed;
  z-index: 1000;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  overflow: auto;
  background-color: rgba(0, 0, 0, 0.75);
}

.modal-content {
  background-color: #fefefe;
  margin: 15% auto;
  padding: 20px;
  border: 1px solid #888;
  width: 80%;
  text-align: center;
}

.close-button {
  color: #aaa;
  float: right;
  font-size: 28px;
  font-weight: bold;
  cursor: pointer;
}
.close-button:hover,
.close-button:focus {
  color: #000;
  text-decoration: none;
  cursor: pointer;
}