* {
  box-sizing: border-box;
  user-select: none;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
  background: radial-gradient(circle at center, #1a1a1a 0%, #0d0d0d 100%);
  margin: 0;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 20px;
  color: #fff;
}

#game {
  background: #111;
  border: 2px solid #444;
  border-radius: 16px;
  padding: 24px;
  width: min(380px, 90vw);
  box-shadow: 0 0 25px rgba(0, 255, 255, 0.1);
  display: flex;
  flex-direction: column;
  align-items: center;
}

h1 {
  font-size: 2.25rem;
  margin-bottom: 10px;
  color: #0ff;
  text-shadow: 0 0 10px #0ff;
}

#status {
  font-size: 1.25rem;
  margin-bottom: 20px;
  color: #f0f;
  text-shadow: 0 0 6px #f0f;
  min-height: 1.5em;
  text-align: center;
}

#board {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  width: 100%;
  max-width: 320px;
  aspect-ratio: 1 / 1;
}

button.cell {
  background: #222;
  border: 2px solid #333;
  border-radius: 12px;
  font-size: 4rem;
  font-weight: bold;
  color: #0ff;
  cursor: pointer;
  display: flex;
  justify-content: center;
  align-items: center;
  transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.3s ease;
  box-shadow: 0 0 10px #0ff40a20;
}

button.cell:hover:not(:disabled) {
  background: #0ff;
  color: #111;
  transform: scale(1.05);
  box-shadow: 0 0 15px #0ff, 0 0 30px #0ff2;
}

button.cell:disabled {
  cursor: not-allowed;
  opacity: 0.6;
  color: #999;
}

#resetBtn {
  margin-top: 24px;
  padding: 12px 28px;
  width: 100%;
  max-width: 320px;
  border: none;
  border-radius: 12px;
  font-size: 1.2rem;
  font-weight: 700;
  background: linear-gradient(to right, #ff00cc, #3333ff);
  color: #fff;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.3s ease;
  box-shadow: 0 0 15px rgba(255, 0, 255, 0.3);
}

#resetBtn:hover {
  transform: scale(1.03);
  box-shadow: 0 0 20px rgba(255, 0, 255, 0.5), 0 0 30px rgba(51, 51, 255, 0.5);
}

@media (max-width: 400px) {
  button.cell {
    font-size: 3rem;
  }
  #resetBtn {
    font-size: 1rem;
    padding: 10px;
  }
}