* {
  box-sizing: border-box;
}

body {
  font-family: Arial, sans-serif;
  text-align: center;
  background: #f4f6f8;
  margin: 0;
  color: #000;
}

body.dark {
  background: #121212;
  color: #fff;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 15px;
  background: #4f46e5;
  color: white;
}

button {
  padding: 8px 14px;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  background: #6366f1;
  color: white;
}

button:hover {
  opacity: 0.9;
}

.controls {
  margin: 15px;
}

input {
  padding: 8px;
  margin: 6px;
  border-radius: 5px;
  border: 1px solid #ccc;
}

.restart {
  background: #ef4444;
  margin: 10px;
}

canvas {
  max-width: 85%;
  margin: 25px auto;
}