contactPage.js import { useTheme } from '@material-ui/core/styles' const useStyles = makeStyles ( styles ) export default function ContactList () { const theme = useTheme () ... < TableCell > < strong style = { { color: theme . palette . primary . main } } > { name } </ strong > index.js import { ThemeProvider } from '@material-ui/styles' import { createMuiTheme } from '@material-ui/core/styles' import { green , orange , red , blue } from '@material-ui/core/colors' const theme = createMuiTheme ({ palette: { primary: blue , secondary: orange }, status: { danger: red } }) ... ReactDOM . render ( < ApolloProvider client = { client } > < StateProvider > < ThemeProvider theme = { theme } > < Router history = { hist } > < Sw...