body {
  background-color: #111;
  color: #fff;
  font-family: 'Segoe UI', sans-serif;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100vh;
  margin: 0;
  text-align: center;
}
h1 { color: #00ffcc; margin-bottom: 20px; }
input, button {
  margin: 8px; padding: 10px;
  border: none; border-radius: 6px;
  font-size: 1rem;
}
input { background-color: #222; color: #fff; }
button {
  background-color: #00ffcc; color: #000; cursor: pointer;
}
button:hover { background-color: #00ddaa; }
#menu, #setup, #game {
  display: none; flex-direction: column; align-items: center;
}
#menu { display: flex; flex-direction: column; }
.board {
  display: grid; grid-template-columns: repeat(3, 100px);
  gap: 10px; margin: 20px 0;
}
.cell {
  width: 100px; height: 100px;
  background-color: #333; color: white; font-size: 2.5rem;
  display: flex; align-items: center; justify-content: center;
  border-radius: 6px; cursor: pointer;
  transition: background 0.2s ease;
}
.cell:hover { background-color: #444; }
#winnerScreen { margin-top: 20px; }
#winnerScreen h2 { color: #00ffcc; }
#winnerScreen button {
  background-color: #00ffcc; color: #000; margin-top: 10px;
}
#winnerScreen button:hover { background-color: #00ddaa; }
.draw-effect { animation: shake 0.4s; }
@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-5px); }
  75% { transform: translateX(5px); }
}