"Comparing to html is nonsensical" No, absoltely not. We are speaking about programming paradigms. We can speak about those without computers, we never have to speak about HTML. A food recipe is a program, what you are executing when you cook, and it is imperative. Going to the restaurant you can achieve the same (the dish) but in a declarative way.

But I compare SQL and HTML for you. In both cases you are creating a text/a script in order to achieve something. The way how you achieve this can be really different in HTML and SQL. You can create a chess algo in SQL, but you cannot in HTML (purely), because in case of declarative language the framework around it strongly limits what the language could do. How would you explain this, if SQL and HTML are the same by nature? Focus on the text you write, because that is your product. Where is a condition is HTML, and why there is not?

Bitmap (like all data: xml, csv, whatever) is not a language in a classical understanding, but if you wanna make it, yes, they are purely declarative.

"It is not a declaration of what you want, but is a definition of what you have" Nope, i can define this without having a computer:

imperative: cooking recipe

functional: assembly line in a factory

declarative: your assistant. or let's make SQL declarative: you ask chatgpt to write a query, and define this query in english

"declarative is restricted to only markup languages" no, the form of the language is irrelevant. CSS is not markup, but still declarative.

Elements of languages cannot be declarative or not, you can only describe the entire language as such, because we are speaking about programming paradigms.

C is assembly at the end of the day, as everything else for the computer itself, but this is irrelevant here. From purely imperative, which is basically machine code to purely declarative (maybe chatgpt?) it's a scale, you put everything somewhere. Functional programming is syntax sugar over iterative, but it's really important one, as it changes how your mind try to solve problems. So basically what I'm saying everything is an abstraction over another one, down below the machine code, but this is just how thing works, not how you use your brain to solve things. I'm saying all this, because not the technical details, the implementations behind is the point when we speak about a purely theoretical classification which programming paradigm is.