var myCssAr = ["StyleSheet1.css", "StyleSheet3.css", "StyleSheet4.css",
                "StyleSheet5.css", "StyleSheet6.css", 
                "StyleSheet11.css", "StyleSheet12.css"];

function getCookie(c_name) {
    var i, x, y, ARRcookies = document.cookie.split(";");
    for (i = 0; i < ARRcookies.length; i++) {
        x = ARRcookies[i].substr(0, ARRcookies[i].indexOf("="));
        y = ARRcookies[i].substr(ARRcookies[i].indexOf("=") + 1);
        x = x.replace(/^\s+|\s+$/g, "");
        if (x == c_name) {
            return unescape(y);
        }
    }
}
function setCookie(c_name, value, exdays) {
    var exdate = new Date();
    exdate.setDate(exdate.getDate() + exdays);
    var c_value = escape(value) + ((exdays == null) ? "" : "; expires=" + exdate.toUTCString());
    document.cookie = c_name + "=" + c_value;
}
function checkCookieAndSetCss() {
    var cssFile = getCookie("cssFile");
    if (cssFile != null && cssFile != "") {
        setCss(cssFile);
    }
    else {
        setCookie("cssFile", myCssAr[0], 365);
        setCss(myCssAr[0]);
    }
}
function changeCss() {
    var cssFile = (document.getElementById('cssSheet').href).substring((document.getElementById('cssSheet').href).lastIndexOf("/") + 1);
    if (cssFile != null && cssFile != "") {
        cssFile = getNextCssFileName(cssFile);
        setCookie("cssFile", cssFile, 365);
        setCss(cssFile);
    }
}
function setCss(file) {
    if (file != null && file != "") {
        document.getElementById('cssSheet').href = cssFolder + file;
    }
}
function getNextCssFileName(fileName) {
    for (var i = 0; i < myCssAr.length; i++) {
        if (myCssAr[i] == fileName) {
            if (i == myCssAr.length - 1) {
                return myCssAr[0];
            }
            else {
                return myCssAr[i + 1];
            }
        }
    }
}