function chgNavColor(foo) {
   var nbt = "a" + foo;
   var obt = "a" + cbtN;
   //alert(nbt + "\n" + obt);
   document.getElementById(obt).style.color = "#618989";
   document.getElementById(nbt).style.color = "#00dfd5";
   //alert(obt + " " + nbt);
   document.getElementById(obt).style.fontWeight = "normal";
   document.getElementById(nbt).style.fontWeight = "bold";
   cbtN = foo;
}

function chgSubNavColor(foo) {
   var nbt = "sna" + foo;
   var obt = "sna" + cbt;
   
   document.getElementById(obt).style.color = "white";
   document.getElementById(obt).style.backgroundColor = "#8CB0B0";
   
   document.getElementById(nbt).style.color = "#74EDE8";
   document.getElementById(nbt).style.backgroundColor = "#2D514F";
   cbt = foo;
}