Arrogant - HTML5 dom with CSS selectors

[Nick Sabalausky (Abscissa)]

On 06/13/2018 09:23 AM, Andrea Fontana wrote:
 > On behalf of the company I work for [1] today I released a new library:
 > arrogant.
 >

Nice!

> It is a fully conformant HTML5 dom library with CSS selectors.
> 

Does this mean that it requires the raw HTML input to already be fully 
conformant HTML5 or simply that it supports and outputs valid HTML5?