Davey, there’s also a highly reasonable chance that if you’ve installed the theme directly from Github by uploading through the admin interface that is what is messing things up. When you do that, Github prefixes the top level folder structure with -master, which means that the files that live below it won’t always find the right pathways and other files. As result you’ll probably be missing things like the footer images, the screenshot in your Themes admin at /wp-admin/themes.php and likely some additional CSS files which are causing your display issues.
I haven’t used it myself though I know the developer well and have heard it works around this issue, but you might try out the Github Updater plugin as a means of installing/updating themes and plugins from Github.
Another solution is to install the theme manually via FTP to your server. Hopefully this will get your display issues sorted.