_renderCrosshairTitle() {
    const {values, titleFormat, style} = this.props;
    const titleItem = titleFormat(values);
    if (!titleItem) {
      return null;
    }
    return (
      <div className="rv-crosshair__title" key="title" style={style.title}>
        <span className="rv-crosshair__title__title">{titleItem.title}</span>
        {': '}
        <span className="rv-crosshair__title__value">{titleItem.value}</span>
      </div>
    );
  }
Render crosshair title.
@returns {*} Container with the crosshair title.
@private