我无法在epubjs-rn中自定义突出显示颜色

import React, { useEffect, useRef } from 'react';
import { Epub, Rendition } from 'epubjs-rn';

const BookReader = () => {
  const renditionRef = useRef(null);

  useEffect(() => {
    if (renditionRef.current) {
      const rendition = renditionRef.current.getRendition();

      // 设置自定义突出显示颜色
      rendition.themes.register('my-theme', {
        'highlight': 'yellow',
      });
      rendition.themes.select('my-theme');
    }
  }, []);

  const handleBookReady = (book) => {
    // 获取rendition对象
    const rendition = book.renderTo('viewer');

    // 保存rendition对象的引用
    renditionRef.current = rendition;
  };

  return (
    <Epub
      src="path/to/your/book.epub"
      flow="paginated"
      onReady={handleBookReady}
    />
  );
};

export default BookReader;