text: 
  function changeHelloWorld(){
      const hello = document.querySelector(".hello")
      hello.innerHTML = hello.innerHTML.replace('H','<span style = "color:lightslategrey">H</span>')
  }
  function changeFamily(){
      const world = document.querySelector('.world')
      const families = ["'Courier New', Courier, monospace","Arial, Helvetica, sans-serif","'Franklin Gothic Medium', 'Arial Narrow', Arial, sans-serif","fantasy","'Lucida Sans', 'Lucida Sans Regular', 'Lucida Grande', 'Lucida Sans Unicode', Geneva, Verdana, sans-serif"]
  
      for(var i=0;i<families.length;i++){
          function attachClosure(i){
              setInterval(function(){
                  world.style.fontFamily = families[i];
                  world.style.color = "blue"
              },1000*(i+1))
      }
      attachClosure(i)
      }
  }
  changeHelloWorld();
  changeFamily();