window.onload = function() { setHeight(); }
window.onresize = function() { setHeight(); }

function setHeight(){
  setDivHeight('content', 115); // <-- mit diesen Maßen experimentieren. Da kann man den offset einstellen
}

// nothing to edit further down
function setDivHeight(div, margin) {
  if (window.innerHeight) {
    if (document.getElementById(div) != null) {
      var height = (window.innerHeight - margin) + 'px';
      document.getElementById(div).style.height = height;
    }
  } else if (document.body.clientHeight){
    if (document.getElementById(div) != null) {
      var height = document.body.clientHeight - margin;
      height = height + 'px';
      document.getElementById(div).style.height = height;
    }
  }
}