include css in ie8

According to this bug report on the jquery site, there may well be a problem in IE8 with appending css files to the dom that contain relative links.
The poster of the bug suggests that adding it as follows may work:
    var style = document.createElement("link");
    style.setAttribute("type", "text/css");
    style.setAttribute("rel", "stylesheet");
    style.setAttribute("href", "xxx.css");
Or that using an absolute url may also work:
Although he goes on to say that any files included through @import within the appended css file will also not load as expected.
I would suggest giving these test cases a whirl to see what loads for you and what doesn't (if it works you should get a grey background in the HTML window):
Method Used in OP's question:
First possible solution from my answer:
Second possible solution from my answer:
If none of these work, it's possible that Chris Fulstow's answer to a similar question may be a viable solution
        function addCSS() {
            var headtg = document.getElementsByTagName('head')[0];
            if (!headtg) {
            var linktg = document.createElement('link');
            linktg.type = 'text/css';
            linktg.rel = 'stylesheet';
            linktg.href = 'CSS/RoundCorners.css';
            linktg.title = 'Rounded Corners';