title: Change text-fill-color with scroll
body: <p>How change text-fill-color with scroll. On start text should be white. When scroll is lower text should be transparent (in background is image).
  I know, that must change text-fill-color from rgba(255, 255, 255, 0) to rgba(255, 255, 255, 1)</p>
  
  <p>Code:</p>
  
  <pre><code>    var bg = document.querySelector('.shadower');
  var text = document.querySelector('.clip-text-bg');
  
  window.addEventListener('scroll', function () {
    var height = window.innerHeight;
    var scroll = window.scrollY;
    var percent = (scroll / height).toFixed(2);
  
    bg.style.opacity = Math.min(percent, .7);
    text.style.opacity = Math.max(1 - (percent * 2), 0);
  })
  </code></pre>
  
  <p><a href="http://codepen.io/Bakr1/pen/EWXdPG" rel="nofollow noreferrer">http://codepen.io/Bakr1/pen/EWXdPG</a></p>