You can combine your 3 separate scripts into one script (see below).
One of the quirks in XSite Pro is that it prefers a plain <style> tag as opposed to <style type="text/css">.
Also, make sure that the case of your added script is exactly the same as is used in the xsp_styles.css.
In this case, it is TD.XSP_MAIN_PANEL.
Code:
<style>
img { border-style: none; }
a:link {text-decoration:none;color: #3B5998;}
a:visited {text-decoration:none;color: #3B5998;}
a:hover {text-decoration:none;color: #3B5998;}
a:active {text-decoration:none;color: #3B5998;}
TD.XSP_MAIN_PANEL { background-repeat: no-repeat; } /* I changed the case to match xsp_styles.css */
</style>