var ie = /msie/i.test(navigator.userAgent);
    var ieBox = ie && (document.compatMode == null || document.compatMode == "BackCompat");

    function checkSize() {
      var canvasEl = ieBox ? document.body : document.documentElement;
      var w = window.innerWidth || canvasEl.clientWidth;
      var h = window.innerHeight || canvasEl.clientHeight;
	  
      document.getElementById("cont").style.height = Math.max(0, h - 170) + "px";

    }

    window.onload = checkSize;
    window.onresize = checkSize;