var h = 100; 
function gross()
{ 
    h++;
    document.pic.height = h;
    if(h < 300)
    {
    window.setTimeout("gross();",1);
    }
} 
function klein()
{ 
    h--;
    document.pic.height = h;
    if(h >100)
    {
    window.setTimeout("klein();",1);
    }
}