As mentioned above, Skeleton is a lightweight CSS framework (or boilerplate, if you prefer this definition) created by Dave Gamache. More specifically, it's two CSS files: the popular normalize.css file and the skeleton.css file.
Mega is a cloud storage and file hosting service offered by Mega Limited, a New Zealand-based company. The service is offered primarily through web-based apps. Mega mobile apps are also available for Windows Phone, Android and iOS.