You can add it inline in here:
PHP Code:
$rss2_output .= "<dt><strong><a href='" . trim($link) . "'>" . htmlspecialchars(trim($title)) . "</a></strong> - " . htmlspecialchars(trim($date)) . " by <em>" . htmlspecialchars(trim($author)) . "</em></dt><dd>" . htmlspecialchars(trim($description)) . "</dd>";
You notice that they use the definition list html to display it. You could add css for that in the Main CSS - probably give the div that it is all in an id and then you can define "#yourid dt" and "#yourid dt" in there, then you wouldn't need to do it inline. Or, you could not use the definition list to output it, but instead use a table or whatever.