CSS Modules are a JS-only third party solution re-invented/re-implemented in a dozen different ways for various JS frontend frameworks. Requires setting up, requires learning an additional library.
If you mean these CSS modules: https://github.com/css-modules/css-modules?tab=readme-ov-fil... then they need to be supported by whatever build chain you use. And you literally need to use them slightly different than normal CSS. E.g. for Vite yuo need to have `.module.css` extension. And they often rely on additional libraries to learn. E.g. you can enable Lightning CSS with aforementioned Vite which comes with its own CSS flavour: https://lightningcss.dev/css-modules.html
If you mean CSS import attributes, they only appeared in 2024 in Chrome and Firefox, early 2025 in mobile Android etc. and they don't provide magical local scoping out of the box: https://caniuse.com/wf-css-modules
But, given that one would need build tools for tailwind as well, the requirement for build tools couldn't have played a role in the choice between the two.
When working with a component-based UI (like in React), the components are typically the unit of reuse. Those CSS classes are used in one place: the component they're defined for. It's annoying to have to come up with a name for them, and to have to work in a separate file, especially if I just want `padding-inline: 4px` or `display: flex`.
Some argue separation of concerns, but CSS is inherently tightly coupled to the structure of your HTML: there's no getting around that. `.foo > ul` breaks if you replace that `ul` child with an `ol`.
I do agree that more intricate styling is harder to read with Tailwind, and I have some other gripes, too, but in general it's a good trade-off for component-based UIs.
This is what OP was talking about:
https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Nest...
I mean, Tailwind is not that different here - you must use a build tool to tree shake the styles, etc.
