function validar(){
	var nome = document.form.nome.value;
	var email = document.form.email.value;
	var assunto = document.form.assunto.value;
	var mensagem = document.form.mensagem.value;
	
	if(!nome || !email || !assunto || !mensagem){
		document.form.submit.disabled=true;
	}else{
		document.form.submit.disabled=false;
	}
}


startList = function() {
	if (document.all&&document.getElementById) {
	navRoot = document.getElementById("nav");
	for (i=0; i<navRoot.childNodes.length; i++) {
	node = navRoot.childNodes[i];
	if (node.nodeName=="LI") {
	node.onmouseover=function() {
	this.className+=" over";
	  }
	  node.onmouseout=function() {
	  this.className=this.className.replace(" over", "");
	   }
	   }
	  }
	 }
	}
	window.onload=startList;