text: /* --------- init showdown --------- */
  
  // showdown links:
  //   syntax   https://github.com/showdownjs/showdown/wiki/Showdown's-Markdown-syntax
  //   examples http://demo.showdownjs.com/
  //   options  https://github.com/showdownjs/showdown/wiki/Showdown-Options
  
  
  // set default classes
  const classMap = {
      h1: 'ui large header',
      h2: 'ui medium header',
      ul: 'ui list',
      li: 'ui item'
    }
    
  const bindings = Object.keys(classMap)
      .map(key => ({
          type: 'output',
          regex: new RegExp(`<${key}(.*)>`, 'g'),
          replace: `<${key} class="${classMap[key]}" $1>`
  }));
    
  // const conv = new showdown.Converter({
  //     extensions: [...bindings]
  // });
  
  // global settings
  showdown.setFlavor('github');
  
  var myconverter = new showdown.Converter({
      tables: true, 
      strikethrough: true,
      tasklists: true,
      extensions: [...bindings]
  })
  
  /* --------- custom script --------- */
  
  /**
   * load md-file into html page
   * example: displayMD('overview.md', 'nl-overview')
   * @param {*} page 
   * @param {*} elementID 
   */
  function displayMD(page, elementID) {
      //
      var node = document.getElementById(elementID);
  
      // using fetch-API: 
      //      https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch
      fetch(page)
      .then(response => response.text())
      .then((data) => {
          html = myconverter.makeHtml(data);
          node.innerHTML = html;
      })
      .catch(error => console.error(error));
  }
  
  /**
   * lookup page for tags and fill with md-content 
   * example: buildMDContent('div', 'nl')
   * @param {*} tagname 
   * @param {*} prefix 
   */
  function buildMDContent(tagname, prefix) {
      // console.log("buildMDContent (tagname="+tagname+", prefix="+prefix+")"); 
      var prefix2 = prefix+'-'
      document.querySelectorAll(tagname).forEach(function(element) {
          var id1 = element.id
          if (id1 != null && id1.startsWith(prefix2)) {
              var name1 = element.id.slice(prefix2.length)
              // console.log(" found <div id='"+element.id+"' />")
              displayMD(name1+'.md', element.id)
          }
  	});
  }
  
  // build content from MD files
  buildMDContent('div', 'nl')