//REGULAR ALTURA

var div = document.getElementById("menuL").clientHeight;
var conteudo = document.getElementById("conteudo").clientHeight;

if (div > conteudo) {
var site = document.getElementById("conteudo");
var siteHeight = site.clientHeight;
var siteSize = parseInt(div-conteudo);
site.style.height = parseInt(siteHeight + siteSize);
}