$(function(){
	
	// 季節写真
	var season_images = new Array;
	season_images[0] = "/common/imgs/top_img_spring.jpg";
	season_images[1] = "/common/imgs/top_img_summer.jpg";
	season_images[2] = "/common/imgs/top_img_autumn.jpg";
	season_images[3] = "/common/imgs/top_img_winter.jpg";
	
	
	var now = new Date();
	var month = now.getMonth() + 1;
	
	
	// ランダム用配列
	var randomimage = new Array(2);
	randomimage[0] = '/common/imgs/top_img_illustration.gif';
	if (1 <= month && month <= 2) {
		randomimage[1] = "/common/imgs/top_img_winter.jpg";
	} else
	if (3 <= month && month <= 5) {
		randomimage[1] = "/common/imgs/top_img_spring.jpg";
	} else
	if (6 <= month && month <= 8) {
		randomimage[1] = "/common/imgs/top_img_summer.jpg";
	} else
	if (9 <= month && month <= 11) {
		randomimage[1] = "/common/imgs/top_img_autumn.jpg";
	} else
	if (12 == month) {
		randomimage[1] = "/common/imgs/top_img_winter.jpg";
	}
	
	
	// ランダムで0か1を生成し、配列の添え字に
	var num = Math.floor(Math.random() * 2);
	$("#header").css("background-image", "url(" + randomimage[num] + ")");
	
	
});