var Datum = new Date();
var Monat = Datum.getMonth() + 1; //start bei 0
if(Monat>=12)
  style = "winter";
else if(Monat>=9)
  style = "autumn";
else if(Monat>=6)
  style = "summer";
else if(Monat>=3)
  style = "spring";
else 
  style = "winter";
  include = "<link rel='stylesheet' type='text/css' href='themes/thai02/"+style+".css' />";

function navi(id1,id2,id3){
  elem=document.getElementById(id1);
  elem.style.display="block";
  document.getElementById(id2).style.display="none";
  document.getElementById(id3).style.display="none";
}
function hide(id1) {
  document.getElementById(id1).style.display="none"; 
}