window.onload = initAll;

function initAll(){
    
    var panelLeftHight = document.getElementById('mainPanelLeft').offsetHeight;
    var panleRightHight = document.getElementById('mainPanelRight').offsetHeight;
    var panelMiddleHight = document.getElementById('mainPanelMiddle').offsetHeight;

    if(panelLeftHight <panleRightHight ){            
            document.getElementById('mainPanelLeft').style.height = panleRightHight+"px";
    }
    if(panelLeftHight >panleRightHight ){            
            document.getElementById('mainPanelRight').style.height = panelLeftHight+"px";
    }
    if(panelMiddleHight >panleRightHight && panelMiddleHight>panelLeftHight){
            document.getElementById('mainPanelRight').style.height = panelMiddleHight+"px";
            document.getElementById('mainPanelLeft').style.height = panelMiddleHight+"px";
    }    
}