function showNav(pos)
         {
         if(document.getElementById(pos))
                  {
                  document.getElementById(pos).style.visibility = "visible";
                  }
         }

function hideNav(pos)
         {
         if(document.getElementById(pos))
                  {
                  document.getElementById(pos).style.visibility = "hidden";
                  }
         }

function change_c(pos1)
         {
         if(document.getElementById(pos1))
                  {
                  document.getElementById(pos1).style.border = "none";
                  document.getElementById(pos1).style.borderWidth = "1px";
                  document.getElementById(pos1).style.borderColor = "#646567";
                  document.getElementById(pos1).style.backgroundColor = "#CECECE";
                  }
         }

function change_b(pos1)
         {
         if(document.getElementById(pos1))
                  {



                  document.getElementById(pos1).style.border = "none";
                  document.getElementById(pos1).style.background = "none";
                  }
         }