No. 30: Web-based Word-like rich text editor in one HTML file

No. 30: Web-based Word-like rich text editor in one HTML file — generated with Nano Banana Pro

What this prompt does: Produces a ugc talking head image using Nano Banana Pro. Style cues: pastel, vibrant. Sourced from a verified CC-BY-4.0 repository (karminski-牙医) and reproduced here unchanged with full attribution per the source license.

Prompt
Help me write a web-based rich text editor similar to {argument name="reference_software_en" default="Word"}, including its main features, with all code contained in a single HTML file. It should support: headings, paragraphs, left alignment, bold, italic, right alignment, underline, strikethrough, background color, text color, numbering, undo, and finally a download function. Directly generate the HTML, and that’s it!