RandomImage = new Array();

RandomImage[0]="http://blog-imgs-12.fc2.com/h/e/a/heartattack507/Header_Back_Image_00.jpg";
RandomImage[1]="http://blog-imgs-12.fc2.com/h/e/a/heartattack507/Header_Back_Image_01.jpg";
RandomImage[2]="http://blog-imgs-12.fc2.com/h/e/a/heartattack507/Header_Back_Image_02.jpg";
RandomImage[3]="http://blog-imgs-12.fc2.com/h/e/a/heartattack507/Header_Back_Image_03.jpg";
RandomImage[4]="http://blog-imgs-12.fc2.com/h/e/a/heartattack507/Header_Back_Image_04.jpg";
RandomImage[5]="http://blog-imgs-12.fc2.com/h/e/a/heartattack507/Header_Back_Image_05.jpg";
RandomImage[6]="http://blog-imgs-12.fc2.com/h/e/a/heartattack507/Header_Back_Image_06.jpg";
RandomImage[7]="http://blog-imgs-12.fc2.com/h/e/a/heartattack507/Header_Back_Image_07.jpg";
RandomImage[8]="http://blog-imgs-12.fc2.com/h/e/a/heartattack507/Header_Back_Image_08.jpg";
RandomImage[9]="http://blog-imgs-12.fc2.com/h/e/a/heartattack507/Header_Back_Image_09.jpg";
RandomImage[10]="http://blog-imgs-12.fc2.com/h/e/a/heartattack507/Header_Back_Image_10.jpg";
RandomImage[11]="http://blog-imgs-12.fc2.com/h/e/a/heartattack507/Header_Back_Image_11.jpg";
RandomImage[12]="http://blog-imgs-12.fc2.com/h/e/a/heartattack507/Header_Back_Image_12.jpg";

xx = Math.floor(RandomImage.length*Math.random());
RandomImage = RandomImage[Math.floor(xx)];
document.write ('<style type="text/css"><!-- .top {background-image: url("'+ RandomImage +'");} --></style>');