var div = new Array();
    
div[0] = document.getElementById("lijevi");
div[1] = document.getElementById("desni");
div[2] = document.getElementById("srednji");
    
var max = 0;
for(var i=0;i<div.length;i++) if(div[i].offsetHeight*1>max) max=div[i].offsetHeight*1;

//68 IE, 61 Firefox
if(document.all)
    max=max-68;
else
    max=max-61; 
//Safari cudan skroz
if(navigator.vendor) 
    max = max+53

if(max<1175)max=1175;
div[0].style.height = max+"px";
div[1].style.height = max-20 + "px";