The DefaultCssUrl variable in configuration.js in your dispatch packages can be used to theme the player. That URL will be automatically translated to/from http or https depending on the protocol used to launch the course and then inserted into the <head> of the player frame as a stylesheet link.
How to alter this variable depends on how you download dispatch packages; if you use the API (specifically the rustici.dispatch.downloadDispatches API call), you can provide a parameter called cssurl that will be automatically inserted into the DefaultCssUrl in configuration.js for you in the downloaded package. Alternately, if you download dispatch packages directly from the website, you'll have to unzip the dispatch package, edit configuration.js by hand, and re-zip the package... which probably isn't feasible as a long-term solution.
I would recommend starting off with the default stylesheet http://cloud.scorm.com/sc/css/cloudPlayer/cloudstyles.css and then customizing that further to your needs.
If you have any questions, just send a message to firstname.lastname@example.org.