A web-based mental math game that trains you in doing math using only your head and nothing more.
It offers an endless mode, where you end the questions only when you want, and a predefined-questions mode, where you assign a specific number of questions you want to solve.
Only HTML5, CSS3 and Javascript, meaning it can be cloned and easily run in any machine/browser.
I did not use any framework for Javascript, as it was an exercise on my knowledge of pure js and html/css.