body { text-align: center; font-family: Arial; background: #f4f4f4; margin: 0; padding: 20px; }
canvas { border: 1px solid #ccc; max-width: 100%; height: auto; }
.color-button {
  width: 40px; height: 40px; margin: 5px;
  border-radius: 50%; border: 2px solid #222; display: inline-block; cursor: pointer;
}
#popup {
  background: #fff; padding: 10px; border: 1px solid #aaa; margin: 10px auto;
  box-shadow: 0 0 10px rgba(0,0,0,0.1); display: inline-block;
}
#toolbar {
  margin: 10px 0;
}
button {
  padding: 6px 14px; margin: 4px; font-size: 14px; cursor: pointer;
}