message: use absolute positioning for chargrid
  fixes
diff: @@ -53,6 +53,7 @@ export default class CharGrid extends Component {
  constructor (props) {
  super(props)
  + this.canvasRef = React.createRef();
  this.font = null
  }
  componentDidMount() {
  @@ -74,7 +75,7 @@ export default class CharGrid extends Component {
  }
  draw (prevProps) {
  - const canvas = this.refs.canvas
  + const canvas = this.canvasRef.current
  const ctx = canvas.getContext("2d")
  if (this.font === null) {
  @@ -137,9 +138,14 @@ export default class CharGrid extends Component {
  const scale = this.props.grid ? 9 : 8
  return (
  <canvas
  - ref='canvas'
  + ref={this.canvasRef}
  style={{
  - backgroundColor: this.props.backgroundColor
  + backgroundColor: this.props.backgroundColor,
  + position: 'absolute',
  + top: '0px',
  + left: '0px',
  + width: `${this.props.width*scale}px`,
  + height: `${this.props.height*scale}px`,
  }}
  width={this.props.width*scale}
  height={this.props.height*scale}>
  