How to build custom form controls: https://developer.mozilla.org/en-US/docs/Learn/Forms/How_to_build_custom_form_controls
For the video element: https://developer.mozilla.org/en-US/docs/Web/Guide/Audio_and_video_delivery/cross_browser_video_player
Semantic Elements in HTML: https://www.w3schools.com/html/html5_semantic_elements.asp
Using HTML sections and outlines: https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/Using_HTML_sections_and_outlines