text:  function addStylesheet(name) {
     const link = document.createElement("link");
     link.type = "text/css";
     link.rel = "stylesheet";
     link.href = safari.extension.baseURI + name;
     document.head.appendChild(link);
   }
  
  const observer = new MutationObserver(() => {
    if (document.body) {
      addStylesheet("build/refined-github.css");
      addStylesheet("safari.css");
      observer.disconnect();
    }
  });
  observer.observe(document, {childList: true, subtree: true})
  