function tabtoggle(tabid){ 
  for(i=0; i<tabs; i++){
    var tab = "tab" + (i+1);
    var tabcontent = "tab" + (i+1) + "content"; 
    if((i+1)==tabid){ 
      document.getElementById(eval("'" + tab + "'")).className = "tabon"; 
      document.getElementById(eval("'" + tabcontent + "'")).style.display = "block"; 
    } 
    else { 
      document.getElementById(eval("'" + tab + "'")).className = "taboffg"; 
      document.getElementById(eval("'" + tabcontent + "'")).style.display = "none";
    } 
  } 
}