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/matteo/"+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"; 

}