The development team working on a project were having trouble obtaining the correct design specs from our design files. In order to facilitate the design-dev handoff, I often created working CodePen demos that showcased element states. Developers were able to use CodePens like this to simply copy and paste the HTML layout and styling of components to utilize in the development of the application.
See the Pen Toggle and Dropdown Styling POC by Samantha Howes (@dusterbed) on CodePen.