Shrink text of a particular class relative to how far scrolled a page is.

shrinky.js

(function shrinky() {

var q = document.querySelectorAll(".shrink");

window.addEventListener(
  "scroll", 
  function scroll () {
    var i, z = 100-(Math.min(window.pageYOffset,100)/2);
    for(i=0; i<q.length; i++) {
      q[i].style.fontSize = z+"%";
    }
  }
);

}());