Adds a settings panel to the WordPress admin that allows you to specify css class or id styles and pages/posts to apply them to.
None that I can think of.
Make sure that when you enter your styles in the options panel, that you haven't included the style tags, which the plugin adds for you. Make sure that you clear/update any caching plugin that you may be using. If you have doubts as to whether your style is being injected in to the page, view the source of your page and look for the css you've supplied in the head section of the HTML for that page.