private static @NotNull String getCssStyleCodeToInject() {
    boolean isDarcula = UIUtil.isUnderDarcula();
    Style style = isDarcula ? Style.DARCULA : Style.DEFAULT;
    String cssCodeToInject = ourLoadedStylesCache.getOrDefault(style, null);
    if (cssCodeToInject != null) return cssCodeToInject;

    try {
      cssCodeToInject = Resources.toString(RestJcefHtmlPanel.class.getResource(style.getCss()), StandardCharsets.UTF_8);
    }
    catch (IOException e) {
      throw new RuntimeException("Failed to load " + style.getCss() + ".", e);
    }

    cssCodeToInject = "<style>" + cssCodeToInject + "</style>";
    ourLoadedStylesCache.put(style, cssCodeToInject);

    return cssCodeToInject;
  }
private static @NotNull String getCssStyleCodeToInject()