I’ve mentioned this before here, but originally I was against Tailwind because it breaks the Cascading part of CSS, however I think a lot of websites lately work better with “locally scoped” styles as there are just so many different components that many things just dont need to follow a global style sheet. So now I usually reach for tailwind first, unless is a relatively simple vanilla html site
Global styles are like global state in software: They're best avoided.
Global state is bad because it’s mutable. Global styles are not mutable.
Global styling done messily can override local styling. It’s the hardest kind of problem to reason about!
I do think that stuff like bootstrap is generally good at avoiding this but it only takes a handful of improperly scoped high level CSS rules to cause awkward hard-to-fix pain much later on.
Learn how cascading works, then learn how to use the web inspector. I'm using Firefox and the style panel list the the selectors used in order of priority. And you can filter by properties to see which one is overriding everything else (i.e the only one not crossed out).
No.. that's not the only reason.
Global state is bad because it makes it hard to reason about your system. The global state can affect any part of it, or, focusing on the inverse which is probably better applied to global styles, any part of your system can depend on the global state.
It's also weird to say "global styles are not mutable" - you're right, they're (generally) not mutable, at runtime. But they are mutable in the sense that your developers (you, or your colleagues, or someone in 3 years maintaining your code) can mutate them, and if large parts of your system are implicitly dependent on the CSS cascading properly and so on, then those changes can have unintended consequences.
Of course, that can also apply to tailwind, to some extent. A developer can change a class (custom or otherwise) or the configuration - but at least it is very clear what is being changed and what parts will be affected (just grep).
With CSS unintended consequences are always problems of scoping things better. If I give semantically meaningful CSS classes to my semantic HTML and scope my rules to apply to their intended place in the pages, then unintended consequences don't happen. If I roll like: "Oh, I want this list to look differently, lets make a global scope ul/ol style!" then I am asking for trouble later on. When I write a CSS rule, I should always be thinking about the scope and whether my rules are truly something universally applicable to that scope.
Says the engineer and not the designer
What does the designer say?
So no CSS files at all? Only inline styles?
No, you just need to scope your styles appropriately. See also my other comment: https://news.ycombinator.com/item?id=48161902
Well I mean styles that are actually global I put into CSS, but it’s generally not too much