I meant to show the CSS you are using to style the plugin output, not your entire CSS file.
What is the name of the CSS class in the "Default CSS class" setting for the plugin? Is it "jpgetrssfeed"? Or are you supplying another class name via the shortcode (or PHP function)? That might explain why the values you entered aren't being applied to the elements under the CSS class.
Is your CSS file being cached, or are you serving a static gzipped version of it? That might explain why changes in your CSS file aren't filtering down to the browser. Clear your browser cache and your caching plugin, and regenerate the gzip version of your CSS file, if applicable.
Are you using Firebug or another source code viewer to see how the CSS is being applied?
If it still doesn't work, make some other changes to your CSS file to confirm that it behaves as expected. This will isolate the problem.
If all else fails, you may need to override any other CSS that may be applied by using the