Accessing Previous Theme Variables In CreateMuiTheme
Answer : You'd need to create an instance of the default theme and use it when defining your own: import { createMuiTheme } from 'material-ui/styles'; const defaultTheme = createMuiTheme(); const theme = createMuiTheme({ typography: { fontSize: defaultTheme.typography.fontSize + 2 } }); export default theme; You can also create your theme and then add on to it after theme is created. import { createMuiTheme } from 'material-ui/styles'; const theme = createMuiTheme(); theme.typography = { ...theme.typography, fontSize: theme.typography.fontSize + 2 } export default theme;