"CSS is not a markup language at all"
Ok. It's a style sheet language. This doesn't change any of the reasons that I've listed as to why people don't prefer working with it.
"all code is about "update source and hit refresh"
No. Not at all.
I either think through logic or literally whiteboard, then write it. I get feedback, think/whiteboard, rewrite, and repeat. Even if a language has a REPL environment, I still am thinking and coming up with logic in order to solve a real problem. Not writing markup and hitting refresh to make sure my div now has rounded borders or whatever.
"coding forms connected to back-end databases through a REST API is boring to others"
In other words, doing dull, mindless drudgery is boring to everyone. Of course I hate linking up REST APIs; it's sometimes necessary but tedious and boring. Frameworks like rails do as much as they can do automate that stuff as well, because people would rather be working on interesting problems.
When I talk about software development, I don't mean "a person having hands on a keyboard inputting characters". I'm talking about a person using reasoning and logic to come up with solutions to actual interesting problems, not "how do I center this div" or "how do I style this webpage".
"Don't conflate CSS development with web design"
CSS development goes hand-in-hand with web design. If one is just writing CSS to conform to a premade design, then it's even more mindless toiling to ensure that it renders correctly across browsers and screen sizes. You may disagree, but it still has -nothing- to do with being feminine or masculine or anything related to that.
"(aside from your own gender-stereotypical opinion on hygiene habits and the validity of making things look good)"
The only person making assumptions here is you. I never stated that it was related to being -male-, I said "programmers". My opinion comes from literally observing people in my own profession. People in other professions don't quite have stereotypes around lacking fashion sense.
"that is noting a trend and not an opinion"
Ascribing femininity to CSS development is literally an opinion. Stating that "men don't value CSS because prettifying things is seen as feminine" is literally an opinion. Nobody that I know in software development has -ever- stated anything even remotely close to this about CSS, or web design, or frontend work in general. Nobody forces anyone to do frontend work, or backend work, or web design, or infrastructure, or... It's a choice.
People simple value other aspects of development because they are more interesting. Trying to imply that CSS is less valued or seen as less interesting because it "might be seen as feminine" is completely divorced from reality. Just insanity.