Stroll Scroll réagit CSSS

const styles = theme => ({
  '@global': {
    '*::-webkit-scrollbar': {
      width: '0.4em'
    },
    '*::-webkit-scrollbar-track': {
      '-webkit-box-shadow': 'inset 0 0 6px rgba(0,0,0,0.00)'
    },
    '*::-webkit-scrollbar-thumb': {
      backgroundColor: 'rgba(0,0,0,.1)',
      outline: '1px solid slategrey'
    }
  }
});
Mjherzalla