change-default-color-App.jsx

import React from 'react';
import Demo from './demo';
import { createTheme, ThemeProvider } from '@material-ui/core/styles';

const Theme = createTheme({
  palette: {
    primary: {
      main: '#d2691e',
    },
  },
});

export default function App() {
  return (
    <div>
      <ThemeProvider theme={Theme}>
        <Demo />
      </ThemeProvider>
    </div>
  )
}