What is an HTML ebook reader?

A thought on what an HTML ebook reader might be.

It converts input of HTML content into a series of reading experience.

The input is a group of HTML files, or a group of content in <sections> in a single page HTML file.

The reader should be:

• Offline readable
• Offline downloadable
• Mobile and desktop friendly
• Able to share particular section or chapter
• Able to comment through twitter sharing
• Able to print as reference. Or print as PDF.