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April 12th, 2021 × #CSS#webdev#frontend

Hasty Treat - CSS Nesting 1

Wes Bos and Scott Tolinski discuss a new CSS draft feature for CSS nesting. They explain the benefits, proper usage, and syntax of CSS nesting. They also discuss how it can be used with media queries and ensure backwards compatibility.

Wes Bos

Wes Bos Host

Scott Tolinski

Scott Tolinski Host

or
Show Notes Transcript

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

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