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

function setBodyStyle()
{
    if (document.getElementById("content").clientHeight > document.getElementById('body').clientHeight
      || document.getElementById("content").clientHeight > document.documentElement.clientHeight
      || document.getElementById("content").clientHeight > document.getElementById('body2').clientHeight)
    {
        document.documentElement.className = 'tall';
    }
    else
    {
        document.documentElement.className = 'short';
    }
}

function setBodyStyleDebug()
{
    s = "content.height = " + document.getElementById("content").clientHeight + 
        '; html.height = ' + document.documentElement.clientHeight +
        '; body.height = ' + document.getElementById('body').clientHeight +
        '; body2.height = ' + document.getElementById('body2').clientHeight + '\n' +
        window.document.width + 'x' + window.document.height + '\n';
    
    if (document.getElementById("content").clientHeight > document.getElementById('body').clientHeight
      || document.getElementById("content").clientHeight > document.documentElement.clientHeight
      || document.getElementById("content").clientHeight > document.getElementById('body2').clientHeight)
    {
        document.documentElement.className = 'tall';
        s += 'tall';
    }
    else
    {
        document.documentElement.className = 'short';
        s += 'short';
    }
    
    window.alert(s);
}