The point was to reimplement a browser. Imagine you want to make an ebook reader,this device needs not to eat too much batteries so you want to implement a basic css and html renderer not to re-skin Chrome.
Some ebook publishing platforms will perform checks and reject your epub(mobi or similar format) if is not respecting some strict rules, this makes it a pain if you have random html that works on web but you want to package it as epub because now you need to find all the bugs(or similar stupid DOM elements) and fix them as best you can.
Some ebook publishing platforms will perform checks and reject your epub(mobi or similar format) if is not respecting some strict rules, this makes it a pain if you have random html that works on web but you want to package it as epub because now you need to find all the bugs(or similar stupid DOM elements) and fix them as best you can.