$(document).ready(function(){
	setBG();
});

function setBG() { $('body').css("backgroundImage", getImage()); }
function getImage(){ var d = new Date(); var m = d.getMonth();
	switch(m) { case 1,2,12: return 'url(/images/bg_main_winter.png)'; case 3,4,5: return 'url(/images/bg_main_spring.png)';
	case 6,7,8: return 'url(/images/bg_main_summer.png)'; case 9,10,11: return 'url(/images/bg_main_autumn.png)'; } }