text: 
  let tiles = document.querySelectorAll('.tile')
  let background = document.querySelector("#bg");
  const options = {
      threshold: .6,
  };
  
  const observer = new IntersectionObserver(
      function (entries, observer) {
          entries.forEach(entry => {
              if(!entry.isIntersecting){
                  return;
              } else {
                  entry.target.classList.add('toggle-opacity');
                  observer.unobserve(entry.target);
              }
          })
      }    
      , options )
   tiles.forEach(tile => {
      observer.observe(tile)
  })
  
  const option = {
      threshold: .2,
  }
  