message: fix Demo header buttons color
diff: @@ -35,35 +35,38 @@ class Demo extends Component {
  <main className={classes.main}>
  <AppBar position="fixed" className={classes.noShadow}>
  <Toolbar>
  - <IconButton className={classes.menuButton} color="contrast" aria-label="Menu">
  + <IconButton className={classes.menuButton} color="inherit" aria-label="Menu">
  menu
  </IconButton>
  <div className={classes.flex} />
  <Tooltip title="Toggle English/French moment locale" enterDelay={300}>
  - <IconButton color="contrast" onClick={toggleFrench}>
  + <IconButton color="inherit" onClick={toggleFrench}>
  language
  </IconButton>
  </Tooltip>
  <Tooltip title="Toggle light/dark theme" enterDelay={300}>
  - <IconButton color="contrast" onClick={toggleThemeType}>
  + <IconButton color="inherit" onClick={toggleThemeType}>
  lightbulb_outline
  </IconButton>
  </Tooltip>
  <Tooltip title="Toggle direction" enterDelay={300}>
  - <IconButton color="contrast" onClick={toggleDirection}>
  + <IconButton color="inherit" onClick={toggleDirection}>
  format_textdirection_l_to_r
  </IconButton>
  </Tooltip>
  -
  - <a href="https://github.com/dmtrKovalenko/material-ui-pickers">
  - <IconButton>
  - <Github color="contrast" />
  + <Tooltip title="Github" enterDelay={300}>
  + <IconButton
  + color="inherit"
  + component="a"
  + href="https://github.com/dmtrKovalenko/material-ui-pickers"
  + >
  + <Github color="inherit" />
  </IconButton>
  - </a>
  + </Tooltip>
  </Toolbar>
  </AppBar>
  @@ -156,6 +159,7 @@ const styles = theme => ({
  main: {
  backgroundColor: theme.palette.background.default,
  marginBottom: -50,
  + color: theme.palette.common.white,
  },
  content: {
  paddingTop: '80px',
  