My understanding is unless he's distributing it (not just serving it from a website) he doesnt need to release his changes. That's what the AGPL is for.
It's not the copyright on the server code that is at issue, but the copyright on the HTML and CSS files (and portions thereof) that get distributed by the server.
You see the contradiction, right? If it's about the HTML and the CSS the user has that code directly by visiting the site. No further action would be needed.
If it's about something that creates the HMTL and CSS, then OP has no requirement because of the GPL just from people visiting the site and accessing the output CSS/HTML. Because that's not distributing the code as defined by the GPL. The original author should have used the AGPL for that case - and if it's really just about HTML/CSS a different license altogether.
> If it's about the HTML and the CSS the user has that code directly by visiting the site. No further action would be needed.
Wrong. Transmitting modified GPL works requires more than just distributing the source:
a) The work must carry prominent notices stating that you modified it, and giving a relevant date.
b) The work must carry prominent notices stating that it is released under this License and any conditions added under section 7. This requirement modifies the requirement in section 4 to “keep intact all notices”.
c) You must license the entire work, as a whole, under this License to anyone who comes into possession of a copy. This License will therefore apply, along with any applicable section 7 additional terms, to the whole of the work, and all its parts, regardless of how they are packaged. This License gives no permission to license the work in any other way, but it does not invalidate such permission if you have separately received it.
d) If the work has interactive user interfaces, each must display Appropriate Legal Notices; however, if the Program has interactive interfaces that do not display Appropriate Legal Notices, your work need not make them do so.
First, that is for Conveying Modified Source Versions. See the definition of conveying:
> To “convey” a work means any kind of propagation that enables other parties to make or receive copies. Mere interaction with a user through a computer network, with no transfer of a copy, is not conveying.
Generally the common position here is to use the AGPL if you want to cover regular network access. Probably all a bit murky because the GPL does not really fit well to things like this. But mostly it does not apply here, pretty specifically by definition.
Maybe you'd have a point regardless if the source was directly the HTML and CSS. And it seems like I was wrong with the modification notice (but I wasn't thinking about modifications in particular). But it's not HTML and CSS directly. Having looked at the source in question now the transmitted HTML and CSS is evidently not the source code, as both is produced by template files.
The actual GPL uses the word "convey", not distribute or serve. [1](section 5). Merriam-Webster defined "convey" as "to transfer or deliver". Pretty hard to argue that a web server does not transfer or deliver HTML + CSS.
