windowResize = function() {
  var div_stills = document.getElementById("stills");
  var div_filminfo = document.getElementById("filminfo");

  if (div_stills && div_filminfo)
    if (document.body.clientWidth > 1150) {
      div_stills.style.width = "315px";
      div_filminfo.style.marginRight = "325px";
    }
    else {
      div_stills.style.width = "155px";
      div_filminfo.style.marginRight = "165px";
    }
}

if (window.addEventListener) {
  window.addEventListener("resize", windowResize, false);
  window.addEventListener("load", windowResize, false);
}
else if (window.attachEvent) {   // IE
  window.attachEvent("onresize", windowResize);
  window.attachEvent("onload", windowResize);
}