getHalfStarStyles = (color, uniqueness) => {
  return `
    .react-stars-${uniqueness}:before {
      position: absolute;
      overflow: hidden;
      display: block;
      z-index: 1;
      top: 0; left: 0;
      width: 50%;
      content: attr(data-forhalf);
      color: ${color};
  }`
}
MEMO: inspired by https://github.com/n49/react-stars.
TODO: should be improved (code-standard & code-size) based on a functional component.
TODO: more delicate fractional star instead of just a half star