In this Hasty Treat, Scott and Wes talk about CSS nesting — what it is, when to use it, and why.

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Show Notes

04:22 - What is it?

06:02 - Why nest?

Easier to read
Easier to write
Prevents refactoring errors, allows for dry-er code. No more typing a parent div 100 times, with a possibility of screwing it up.

08:13 - When to use nesting

Nesting is often overused
Only nest what you would have written un-nested with a short hand (e.g. don’t nest just for the sake of it)
- .container .item {} .container .item a {}
Use it for scoping

10:06 - Nesting prefixes

In order to nest CSS, you must first start it with a nesting selector

 .tweet {   & > p {   }   &.media-included { color: green; }   & + .tweet { } // sibling   & p { } // descentang }

Component-based — tweet, card, company, Link

 article{     color: blue;   & {         color: red;   } }

and must be the first child of a compound selector

12:44 - @nest rule / media queries

Mostly just a visual way to show nested

 .foo {     display: grid;     @media(orientation: landscape) {     & {             grid-auto-flow: column;         }     } }

 .foo {   display: grid;    @media (orientation: landscape) {     & {       grid-auto-flow: column;     }      @media (min-inline-size > 1024px) {       & {         max-inline-size: 1024px;       }     }   } } /* equivalent to    .foo { display: grid; }     @media (orientation: landscape) {      .foo {        grid-auto-flow: column;      }    }     @media (orientation: landscape) and (min-inline-size > 1024px) {      .foo {        max-inline-size: 1024px;      }    }  */

16:30 - How to use nesting today

Literally any CSS preprocessor
PostCSS to use spec

Links

Syntax 274: How does stuff get added to CSS? Adam Argyle answers!
Sass
PostCSS
CSS Variables

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