WimTV Framework are made of high-level building blocks called components. Components allow you to quickly design an interface for your Web TV. WimTV Framework comes with a number of components, including video player, thumbnail, and panels.
The layout is based on CSS Flexbox and Bootstrap framework. Bootstrap includes a responsive, mobile first fluid grid system that appropriately scales up to 12 columns as the device or viewport size increases. It includes predefined classes for easy layout options, as well as powerful mixins for generating more semantic layouts. Here you can find the explanation of Bootstrap Grid System.