Most Mario Kart Wii RTA speedruns require that each track's in-game time be summed up and provided with the submission to the leaderboard. This is a convenient user interface to assist with adding up the times when scrubbing through a video.
As a bonus, runs can be exported to and imported from Splits.io for convenient storage and retreival.
This project was originally written in Polymer, which became lit-element, and then just lit. It builds with rollup and generates a service worker for PWA offline functionality.