// JavaScript Document

function testHeight() {
        var d = document.getElementById('box_a');
        var r = document.getElementById('box_b');

        if (r.offsetHeight < d.offsetHeight) { 
        		r.style.height = d.offsetHeight +'px';
        		}
				
		else	{
				d.style.height = r.offsetHeight +'px';
        		}
}

onload=function(){
	testHeight();
}