body {
  font-family: sans-serif;
  background: #f0f0f0;
  margin: 0;
  padding: 0;
  color: #333;
}
header, footer {
  background: #2c3e50;
  color: white;
  text-align: center;
  padding: 1em 0;
}
main {
  padding: 20px;
  max-width: 800px;
  margin: auto;
  background: white;
}
#game-container {
  text-align: center;
  margin-bottom: 2em;
}
#game-board {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  width: 300px;
  margin: 0 auto 10px;
}
.tile {
  width: 70px;
  height: 70px;
  background: #cdc1b4;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  font-weight: bold;
  color: #776e65;
  border-radius: 4px;
}
button {
  padding: 10px 20px;
  font-size: 16px;
}
@media (max-width: 600px) {
  #game-board {
    width: 90vw;
    grid-template-columns: repeat(4, 1fr);
  }
  .tile {
    width: 20vw;
    height: 20vw;
    font-size: 5vw;
  }
}