[seanwilson]

Can anyone explain how deep use of the CSS cascade is any different to OOP inheritance over composition? This is usually discouraged in OOP languages now because it quickly gets confusing and hard to maintain.

Multiple inheritance is also usually discouraged for similar reasons, but not in CSS in the way you can combine classes together without restriction (with `!important` and specificity on top of this).

And is CSS cascading actually a good approach that scales to complex UIs and designs? Is this approach successful anywhere else or is there a way to do styling that's closer to regular programming? CSS seems to be in its own world with lots of debates about best practices.

[chrisweekly]

The CSS cascade, leveraged properly, is perfectly compatible with the principle of favoring composition over inheritance. See https://every-layout.dev/rudiments/composition/

A good approach that scales will use the cascade instead of fighting it. That means global rules and carefully-applied exceptions, with rules' specificity inversely proportional to their reach:

> Sensible CSS architecture has “reach” (how many elements are affected) inversely proportional to specificity (how complex the selectors are). This was formalized by Harry Roberts as ITCSS, with IT standing for Inverted Triangle. ^ https://every-layout.dev/rudiments/global-and-local-styling/

[seanwilson]

> is perfectly compatible with the principle of favoring composition over inheritance

I understand you can use composition over inheritance (like in say Java) but by only using the cascade in limited ways (e.g. global styles), doesn't this demonstrate that the cascade doesn't scale and should generally be avoided?

[chrisweekly]

I guess it depends on your definitions for "limited", "global styles", or "scale". :)

https://every-layout.dev prescribes use of a robust global .css stylesheet with global and element selectors, paired with a brilliant and flexible typography-based scale, custom properties (think "design tokens"), and dedicated layout primitives, that combine to do nearly all the styling work a site could need. There's a place for utility classes as needed. By embracing the cascade and leveraging it properly -- ie, its exception-based paradigm -- it hugely reduces the amount of CSS you need to write (which is otherwise so typically bloated, radically over-specified, and brittle). It's hard to overstate how profoundly different and better our use of CSS can be, when it's based on the axioms so beautifully illustrated by https://every-layout.dev.

FTR I'm not affiliated in any way, just a huge fan of their imho singular work.

[eurasiantiger]

If only there was a way to generate a minimal cascade from a given set of styles. Sort of automatically detect properties that can be moved to a common parent.

One would necessarily have to generate the HTML, too, otherwise there are no guarantees, and even then the CSS—browser interplay might lead to broken styles.

[chrisweekly]

Remix^1 has an interesting approach here; they encourage use of traditional CSS (vs CSS-in-JS), but the styles for a given route are scoped to the component.

1. https://remix.run/docs/en/v1/guides/styling

[eurasiantiger]

That’s a good fit when each route needs a lot of custom styles and each one is developed by a separate team.

However, it doesn’t really fit well if a brand-themed app is developed by a single team. Consistency is easier to maintain when styles can be reused across the application, and things like styled-components don’t work that well there since they tightly couple components to styles, so you need a theming system on top of them… which is silly, because CSS itself is a theming system.

CSS modules is a bit better, but even that encourages encapsulation which is necessarily broken if the styles need to be shared between components.

[chrisweekly]

You seem to have misunderstood; Remix promotes the use of bog-standard CSS. Literally nothing about it in any way inhibits reuse of styles across the app. Not sure where you're going in critiquing styled-components.

[eurasiantiger]

Well, does it keep the styles with the components, or does it expect devs to create a separate folder for shared styles? If there are lots of shared styles, that equates to having two sets of components: one React, the other CSS.

[ozim]

It is the same in CSS as in OOP.

Inheritance is good and nice but...

You should not build 20 layers of it. You can build really nice CSS layout where components are separated and that is idea of component frameworks. There you have maybe 2 layers of cascade and that is it.

So it is people building castles in the sand thinking they are smart, until water comes in and all is washed away.