Make the SVG-based subtitles smaller on Netflix web player

NetflixSmallerSubtitles.js

// Only applied for "image-based timed text" (i.e. SVG-based, like Chinese, Japanese, ...)
// For DFXP-based subtitles (e.g., English), try the hidden settings: https://www.netflix.com/SubtitlePreferences
(() => {
  const installScaler = () => {
    const subRectElem = document.querySelector('rect.image-based-subtitles-rect');
    if (subRectElem) {
      const subWrapperElem = subRectElem.parentNode;
      
      const MutationObserver = window.MutationObserver || window.WebKitMutationObserver;
      const config = {attributes: true, childList: true, characterData: true, };
      const subChangeObserver = new MutationObserver((mutations) => {
        [].forEach.call(subWrapperElem.querySelectorAll('image'), (subImgElem) => {
          if (subImgElem && !subImgElem.classList.contains('scaled')) {
            subImgElem.classList.add('scaled');
            subImgElem.style.display = 'none';

            //// Edit this ////
            const scaleRatio = 0.5;
            ///////////////////

            const origWidth = subImgElem.getAttribute('width');
            const origHeight = subImgElem.getAttribute('height');
            const newWidth = Math.floor(origWidth * scaleRatio);
            const newHeight = Math.floor(origHeight * scaleRatio);

            const origX = Math.floor(subImgElem.getAttribute('x'));
            const origY = Math.floor(subImgElem.getAttribute('y'));
            const newX = Math.floor(origX + 0.5 * (origWidth - newWidth));
            const newY = Math.floor(origY + 0.5 * (origHeight - newHeight));

            subImgElem.setAttribute('width', newWidth);
            subImgElem.setAttribute('height', newHeight);
            subImgElem.setAttribute('x', newX);
            subImgElem.setAttribute('y', newY);
            subImgElem.style.display = '';
          }
        });
      });
      subChangeObserver.observe(subWrapperElem, config);
      return true;
    }
    return false;
  }

  if (window.location.href.toLowerCase().indexOf('netflix.com/watch') != -1) {
    const interval = setInterval(() => {
      if (installScaler()) {
        console.log("Subtitle scaler installed!");
        clearInterval(interval);
      }
    }, 1000);
  }
})();