The mobile first concept is to design a site by designing the mobile version as a priority and gradually adapting it for larger screens. This way of proceeding is contrary to the ordinary way of progressively degrading a website to suit a smaller screen display.
This approach can be useful for websites and web applications that are mainly used on mobile. It has the advantage of adding effects / features for the big screen instead of removing for the little ones.
This is how the Toucan Toco solution is developed in order to have the same functionalities on all screens.