It looks like there’s another set of CSS definitions, either from your theme, or from another plugin, which is bleeding into the CSS that WP Biographia defines, probably overriding one or more components of ul.wp-biographia-list-text.li
(see /wp-content/plugins/wp-biographia/css/wp-biographia.css
at around line 66).
I’d look at your site in the web inspector tool in Chrome or Firebug in Firefox (or another browser’s equivalent) to see if you can spot anything immediately obvious.
If nothing is immediately apparent, then I’d suggest reverting to a stock WordPress supported theme (such as TwentyTen) to see whether the problem goes away. If it does, then it’s probably some CSS in your theme.
If it doesn’t, then it’s more likely to be one of your plugins that isn’t playing well with WP Biographia. In this case, going through each plugin and disabling it and re-checking whether the problem goes away should help to pinpoint the source.
This isn’t an uncommon problem. There’s so many possible permutations of themes and plugins, that it’s almost impossible to check for theme/plugin incompatibilities.
Let me know what you find and how you get on and we can see how next to proceed.
-Gary