Some resources
- https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/Editable_content
- https://blog.whatwg.org/the-road-to-html-5-contenteditable
- https://www.quirksmode.org/dom/execCommand.html
- https://developer.mozilla.org/en-US/docs/Web/Events/keypress
- https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/keyCode