AfterAales/themes/next/source/css/_common/components/reading-progress.styl

.reading-progress-bar {
  background: unquote(hexo-config('reading_progress.color'));
  display: block;
  height: unquote(hexo-config('reading_progress.height'));
  left: 0;
  position: fixed;
  width: 0;
  z-index: $zindex-5;

  if (hexo-config('reading_progress.position') == 'bottom') {
    bottom: 0;
  } else {
    top: 0;
  }
}