function resize() {
	var conteudo = document.getElementById('conteudo').offsetHeight;
	var lateral = document.getElementById('lateral').offsetHeight;
	
	if (conteudo > lateral) {
		document.getElementById('box_conteudo').style.height = (conteudo + 30) + 'px';
	} else {
		document.getElementById('box_conteudo').style.height = (lateral + 30) + 'px';
	}
}

window.onload = resize;
window.onresize = resize;