Grid component has extra 8px with the width?

[wulingmei]

import React from 'react';
import PropTypes from 'prop-types';
import { withStyles, createStyleSheet } from 'material-ui/styles';
import AppBar from 'material-ui/AppBar';
import Toolbar from 'material-ui/Toolbar';
import Typography from 'material-ui/Typography';
import Button from 'material-ui/Button';
import IconButton from 'material-ui/IconButton';
import MenuIcon from 'material-ui-icons/Menu';
import Paper from 'material-ui/Paper';
import Grid from 'material-ui/Grid';

const styleSheet = createStyleSheet(theme => ({
  root: {
      width:'100%',
    flexGrow: 1,
  },
  container:{
      marginTop:'30px',
  },
  flex: {
    flex: 1,
  },
}));

function Main(props) {
  const classes = props.classes;
  return (
      <div className={classes.root}>
        <AppBar position="static" color="accent">
                <Toolbar>
                    <IconButton color="contrast" aria-label="Menu">
                        <MenuIcon />
                    </IconButton>
                    <Typography type="title" color="inherit" className={classes.flex}>
                        美美，我爱你
                    </Typography>
                    <Button color="contrast">登录</Button>
                </Toolbar>
        </AppBar>
        <Grid container >
                <Grid item xs>
                    sdf
                </Grid>
        </Grid>
      </div>
  );
}

Main.propTypes = {
  classes: PropTypes.object.isRequired,
};

export default withStyles(styleSheet)(Main);

[oliviertassinari]

It's a duplicate of #7466.

[wulingmei]

<Grid container spacing={0}>
                <Grid item xs>
                    <ImageGridList/>
                </Grid>
            </Grid>

that is OK