var h; 
  var m; 
  var s;
  var datum;
  datum = new Date();
  
  with (datum){
    h = getHours();
    m = getMinutes();
    s = getSeconds();
  }
 
  if((h>=19)||(h<6))document.write("<link href=\"style/stylesNight.css\" rel=\"stylesheet\" type=\"text/css\"><link href=\"style/menuNight.css\" rel=\"stylesheet\" type=\"text/css\">");