Imported HTML file progress is misleading

The reading progress bar is very misleading or inaccurate when reading imported HTML files. I am not sure how this progress is calculated. For a ~500 word blog post, imported as HTML, the bookreader app starts saying 1/3, then turn the page and it changes to 2/5, then by the end of the book, it changes to 3/3. This is very confusing.

In Kindle (hardware Kindle and Android app), the progress is given as a somewhat arbitrary "location" unless the book has information on page numbers from the physical book mapped to the ebook.

Perhaps this can be calculated using bytes or characters, or by virtual pages (based on how many bytes or chars appear on each page.