function getRand(){
    return Math.round(Math.random()*(css.length-1));
}
var css = new Array(
'<link rel="stylesheet" type="text/css" href="css/spring.css">',
'<link rel="stylesheet" type="text/css" href="css/spring1.css">',
'<link rel="stylesheet" type="text/css" href="css/spring2.css">',
'<link rel="stylesheet" type="text/css" href="css/spring3.css">',
'<link rel="stylesheet" type="text/css" href="css/spring4.css">',
'<link rel="stylesheet" type="text/css" href="css/summer.css">',
'<link rel="stylesheet" type="text/css" href="css/summer1.css">',
'<link rel="stylesheet" type="text/css" href="css/summer2.css">',
'<link rel="stylesheet" type="text/css" href="css/summer3.css">',
'<link rel="stylesheet" type="text/css" href="css/summer4.css">',
'<link rel="stylesheet" type="text/css" href="css/winter.css">',
'<link rel="stylesheet" type="text/css" href="css/winter1.css">',
'<link rel="stylesheet" type="text/css" href="css/winter2.css">',
'<link rel="stylesheet" type="text/css" href="css/winter3.css">',
'<link rel="stylesheet" type="text/css" href="css/winter4.css">',
'<link rel="stylesheet" type="text/css" href="css/autumn.css">',
'<link rel="stylesheet" type="text/css" href="css/autumn1.css">',
'<link rel="stylesheet" type="text/css" href="css/autumn2.css">',
'<link rel="stylesheet" type="text/css" href="css/autumn3.css">',
'<link rel="stylesheet" type="text/css" href="css/autumn4.css">',
'<link rel="stylesheet" type="text/css" href="css/night.css">',
'<link rel="stylesheet" type="text/css" href="css/night1.css">',
'<link rel="stylesheet" type="text/css" href="css/night2.css">',
'<link rel="stylesheet" type="text/css" href="css/night3.css">',
'<link rel="stylesheet" type="text/css" href="css/night4.css">'
);
rand = getRand();
document.write(css[rand]);