function togglePurDec(evt){
  evt = (evt) ? evt :event
  var target = (evt.target) ? evt.target : evt.srcElement
  var block_info = document.getElementById("livros-info");
  var block_adm = document.getElementById("livros-adm");
  if (target.id == "livrostab-adm-a"){
    block_adm.style.display = "block";
    block_info.style.display = "none";
    document.getElementById("livrostab-adm-a").className = "selected";
    document.getElementById("livrostab-info-a").className = "nselected";
  }
  if (target.id == "livrostab-info-a"){
    block_adm.style.display = "none";
    block_info.style.display = "block";
    document.getElementById("livrostab-adm-a").className= "nselected";
    document.getElementById("livrostab-info-a").className= "selected";
  }
}