From Fedora Project Wiki

CSS and Images

One can find all CSS files and images used in the Fedora sites on the web. And we encourage the community to use them directly from our urls in a cascading implementation.

This is especially true when working on official fedoraproject.org domains ( things on this list ):

Websites/DomainsList

Fedora CSS in your application

Load the main Fedora CSS file

And then load your custom css file and override elements as needed:

/w/skins/fedora/main.css or /css/fedora_planet.css

Fedora Images in your application

Images simply need to be loaded via their 'href' attributes' url: