"createMuiTheme"函数接受键集有限的对象.(调色板，版式，间距等)

"createMuiTheme" function accepts object with limited set of keys.(palette, Typography, spacing...etc)

您只能使用普通对象.

const theme = {
  shadowing: {
     boxShadow: "0 2px 5px -1px rgba(0, 0, 0, 0.3)",
  }
};