// d. = this function returns browser-specific integer of content viewport on screen
// (available height for content, taking out toolbar, statusbar, googlebar, etc)
// it takes an optional argument to decrement the total returned, for flexibility
// when setting heights
function detectScreenContentHeight ( decrement ) {
  var contentViewport = 0;
  if (decrement && typeof decrement == 'number') {
    contentViewport -= decrement;
  }
  // all except MSIE
  if (self.innerHeight ) {
    return (contentViewport + self.innerHeight);
  }
  // MSIE in strict mode
  if (document.documentElement && document.documentElement.clientHeight ) {
    return (contentViewport + document.documentElement.clientHeight);
  }
  // MSIE not in strict mode
  if (document.body && document.body.clientHeight ) {
    return (contentViewport + document.body.clientHeight);
  }
}