材质UI网格在Chrome DevTools设备工具栏上不起作用

import '@material-ui/core/styles';
import '@material-ui/core/Grid';

import { createMuiTheme, ThemeProvider } from '@material-ui/core/styles';

const theme = createMuiTheme({
  breakpoints: {
    values: {
      xs: 0,
      sm: 600,
      md: 960,
      lg: 1280,
      xl: 1920,
    },
  },
});

function App() {
  return (
    <ThemeProvider theme={theme}>
      {/* Your components here */}
    </ThemeProvider>
  );
}

import React from 'react';
import { Grid } from '@material-ui/core';

function MyComponent() {
  return (
    <Grid container spacing={3}>
      <Grid item xs={12} sm={6} md={4}>
        Content 1
      </Grid>
      <Grid item xs={12} sm={6} md={4}>
        Content 2
      </Grid>
      <Grid item xs={12} sm={6} md={4}>
        Content 3
      </Grid>
    </Grid>
  );
}