winform咋整好看

1. 透明背景
   https://wenku.baidu.com/view/6f901d5a1411cc7931b765ce05087632311274f8.html
   https://blog.csdn.net/qq_34059233/article/details/119601631
2. picturebox重绘为圆形
   https://www.cnblogs.com/txwtech/p/15371332.html
3. 不显示button边框
   https://blog.csdn.net/weixin_39891262/article/details/111533958