Sigil CSS parser will not understand the new nested CSS

[KevinH]

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 ...

[JSWolf]

Originally Posted by KevinH

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 ...

I agree that devs these devs just don't follow the rules for KISS. Look at a lot of eBooks and you'll see that the code can be quite a mess.

As for nested CSS, I'm not for it at all.

[theducks]

Originally Posted by KevinH

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 ...

Or just because you can do it, that you SHOULD
I wonder if this is just another case of planned obsolescence so you MUST by a new one?

[KevinH]

Either way, I was able to use the Google AI to help write a CSSDenester.h code that will flatten nested css back to "normal" unnested css.

I have added it my personal c++ std::string cssparser repo. I will next take that code and rewrite it using Qt's QString and once tested will add it to Sigil's internal qCSSParser implemetation.

That way future versions of Sigil will produce flattened CSS when you reformat your css. That way your css is kept as viable as possible for older epub e-readers.

(In other words I was too lazy to completely rewrite our current cssparser to be tree based!).

Update:

This has now been added to Sigil master for testing.

[DNSB]

For anyone interested in testing, here's a link to my compile of the latest code from Sigil's Github repository: Sigil-2.7.6-Windows-x64-Setup.exe.

[KevinH]

Thanks! If anyone is looking for some small css testcases that use nesting, see

https://github.com/Sigil-Ebook/cssparser

And grab nesttest*.css and you can drag and drop them on Sigil.

To flatten the css back to normal simply use the reformat css multiline or single line routines.