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The CSS Cascade (2020)

79 points| IA21 | 3 years ago |wattenberger.com

33 comments

order

TAKEMYMONEY|3 years ago

> Let’s take a look at the different tiers of the Cascade

Bad way of framing this, the navigation and phrasing makes it sound like we're going from least to most specific as we scroll down the page but we're not.

> The hierarchy here is actually reversed for !important rules, meaning that an !important browser default rule wins over an !important website rule

I think this would be difficult for a beginner or even intermediate to understand. This chart does a much clearer jobs including every layer of specificity (including with @layer): https://webkit.org/wp-content/uploads/cascade-layers-2048x11...

I appreciate going for an approachable fun way to deliver a dry, complicated topic. Maybe look at how MDN writes about this stuff and get some of the specifics/technicals nailed down a little more.

https://developer.mozilla.org/en-US/docs/Learn/CSS/Building_...

bryanrasmussen|3 years ago

having hard time to think of any default browser rules that use !important, any ideas?

captainmuon|3 years ago

Huh, I always thought the cascade referred to the fact that certain properties apply to child elements (like font size) and others don't (like borders). There are cascading and non-cascading properties. What is described here I would call the specifity (which is actually only one part of it).

The funny thing is that I even implemented a CSS parser and evaluator without knowing the official terms.

seumars|3 years ago

I had the same thought. Property inheritance could be a more specific description though?

chrisweekly|3 years ago

https://every-layout.dev remains, hands-down, the best resource on CSS I've ever encountered since I started working in webdev 24 years ago.

See also this recent post by Josh Comeau, which does a good job explaining layout modes: https://www.joshwcomeau.com/css/understanding-layout-algorit...

farleykr|3 years ago

I second https://every-layout.dev. I was amazed to find out how straightforward the CSS is to accomplish the common layouts we see across the web. CSS is always a tricky one for me but every time I learn about modern CSS I get excited about how you can accomplish more and more while writing less and less CSS/

mocana|3 years ago

Article a reminder of why CSS is so difficult to work with. Turns out I knew all these precedence rules, however when time comes to look at an element and figure out how to make it, say, wider, figuring out WHERE to add that rule is a challenge.

rosmax_1337|3 years ago

I find her website to be difficult to skim and overview, something which is essential for technical reading, because more often than not you will want to return to a document you have previously read to remind yourself of a detail that you remember there, somewhere.

It's probably not only related to the wacky sidebar, but more related to the main content style, headlines being too large and an overuse of colors and emphasis in each section of text. Choosing to alternate dark and light scheme in the A/B code blocks doesn't seem right either.

Which in a way is neither here nor there, since it's not related to her content. Personally I find the "Funky fact alert! The hierarchy here is actually reversed for..." style of writing to be offputting, but I'm sure some others like it.

spiderfarmer|3 years ago

I do and I enjoyed her other articles as well, partly because of how it is worded and designed.

lancesells|3 years ago

I'm all for utility but in this instance that sidebar really makes me appreciate the care and effort that went into it.

seanwilson|3 years ago

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|3 years ago

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/

eurasiantiger|3 years ago

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.

ozim|3 years ago

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.

spansoa|3 years ago

> When we add !important to the end of our declaration, it jumps to this level of the Cascade. Ideally, you reserve this level for Hail Marys, which are needed to override styles from third-party libraries

Or when you write Stylus[0] themes to create custom skins for your favorite sites. Sometimes the Stylus theme doesn't honor what you've coded, and you have to manually over-ride with an !important

[0] https://addons.mozilla.org/en-US/firefox/addon/styl-us/

dncornholio|3 years ago

Which rules wins is the rule that is the most specific. This article explains it as having 'the most hits'. Whatever that means.