CSS animations and transitions played a big part in the development of the menus and non-gameplay elements of the game. Most of these CSS transitions occur during screen transitions or game events, such as showing/hiding the pause menu, transitioning between levels, or transitioning between a level and the level picker. In browsers like Internet Explorer 10, every pixel on the screen is hardware accelerated. What does that mean? It means that without any extra code you have the power to create high fidelity, high performance effects. This helped us offload some of the rendering work from the already abused canvas to the DOM and CSS layout engine.