affiliate link HTML messes up my HTML for the h1 tag

Hello, folks; I have Xara3D4 and I love it. On my website I had a link for my affiliate program and for some weird reason, the HTML tag for h1 (largest headings) now will not work anywhere on my page. The h1 headings are much smaller than the h3 tag even. The page lives at http://www.sticksite.com/ and I have made the code for the Xara affiliate into a remark, deactivating that html. That's all it took to make the h1 tag work again. This is VERY weird, imho.
Can anyone please bring me up to speed?

You are trying to use HTML 5 which has not been released yet. Very few browsers support it. The CSS validated just fine so no CSS 3 was used, but your syntax for HTML 5 is incorrect. 112 HTML errors. This is really incorrect:

Code:

---

<style type="text/css">
        img {                        /* this avoids a border on an image which is a LINK */
                border: none; }
}
</style>

---

Should be:

Code:

---

<style type="text/css">
a img { /* this avoids a border on an image which is a LINK */
text-decoration: none;
border: 0; }
</style>

---

<base target="_blank"> is not needed unless you are using frame pages.

All those embedded style tags could be removed except for one set.