A small sample javascript app done for a frontend dev interview in 2016. Time frame was 1 week.
The assignment specified that NO framework for CSS/LESS/SASS or Javascript may be used, with a few exceptions. I decided to go completely vanilla and use only CSS (with Media Queries) and Javascript with ES5 syntax and some widely supported ES6 features. I also used PHP for the server side component, making some basic database scripts for online data storage. The design is responsive and will switch from a mobile layout to a desktop layout automatically when it goes below a certain threshold.