function season(s) {document.body.id = s}
function cs() {
var now = new Date();
var int = now.getMonth() + 1;
if ( int == 1 || int == 2 || int == 12 )   {season('zima');}
if ( int == 3 || int == 4 || int == 5 )   {season('vesna');}
if ( int == 6 || int == 7 || int == 8 )   {season('leto');}
if ( int == 9 || int == 10 || int == 11 )   {season('osen');}
}