MobileRead Forums - View Single Post - Sigil CSS parser will not understand the new nested CSS

KevinH · 04-07-2026, 10:02 AM

Hi All,

Just a warning. Sigil's CSS Parser which is used throughout the Sigil Reports codebase and a few other places does not understand the new (2025) allowed nested css structure.

https://developer.mozilla.org/en-US/.../Nesting/Using

I would guess that is true for most epub ereaders not based on very very recent webkit/webengine browsers. So using it will limit your base for your epub.

Personally, I think the ability to nest css selectors inside each other is for the birds when it adds nothing and the first thing the downstream software generally does is flatten it back to a simple list an no one wants to process a second tree inside the html DOM tree.

So if you do attempt to write and use nested css in Sigil be prepared for it to get mangled.

Most of the younger devs never seem to have learned about the KISS principle of engineering. So sad. Or is this just my age showing ...

04-07-2026, 10:02 AM	#1
KevinH Sigil Developer Posts: 9,564 Karma: 6774048 Join Date: Nov 2009 Device: many	Sigil CSS parser will not understand the new nested CSS Hi All, Just a warning. Sigil's CSS Parser which is used throughout the Sigil Reports codebase and a few other places does not understand the new (2025) allowed nested css structure. https://developer.mozilla.org/en-US/.../Nesting/Using I would guess that is true for most epub ereaders not based on very very recent webkit/webengine browsers. So using it will limit your base for your epub. Personally, I think the ability to nest css selectors inside each other is for the birds when it adds nothing and the first thing the downstream software generally does is flatten it back to a simple list an no one wants to process a second tree inside the html DOM tree. So if you do attempt to write and use nested css in Sigil be prepared for it to get mangled. Most of the younger devs never seem to have learned about the KISS principle of engineering. So sad. Or is this just my age showing ... Last edited by KevinH; 04-07-2026 at 11:01 AM.