The Hidden Features Of CSS

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CSS POTLUCK

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BENIFITS OF A POTLUCK

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THE HIDDEN Features of CSS

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CRITICAL PATH

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NOTHING RENDERS UNTIL THE CRITICAL PATH IS DONE

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UNTIL CSS IS DONE-DONE NOTHING RENDERS

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GOOGLE DOESN'T LIKE RENDER BLOCKING CSS

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INLINE THE CSS

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Document body { background: red; color: #fff;} Content

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DON'T @import

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BODY LINKS

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... body { background: red; color: #fff;} content sidebar footer

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FIREFOX

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JS IS BLOCKED BY CSS!

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CDN FOR CSS CAN BE BAD

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BASE 64 ENCODED IMAGES IN CSS BE BAD

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HTTP2 DOWNLOADS LOTS OF FILES AT

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CDN

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JAVASCRIPT DEFER AND ASYNC

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JS IS BLOCKED BY CSS!

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ASYNC CSS?

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JS and CSS preload example

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CSS PROCESSING ORDER

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KEY SELECTOR

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#NAV LI A {}

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DON'T OVER QUALIFY SELECTORS #nav li a {} #nav a {} better yet .nav-link {}

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METHODOLOGIES ▸ Atomic ▸ OOCSS ▸ SMACSS ▸ BEM

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▸ Tailwind ▸ Tachyons

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PARSE SPEED

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#nav .nav-link .nav-link span .nav-link * *

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▸ ID, e.g. #header ▸ Class, e.g. .promo ▸ Type, e.g. div ▸ Adjacent sibling, e.g. h2 + p ▸ Child, e.g. li > ul ▸ Descendant, e.g. ul a ▸ Universal, i.e. * // Attribute, e.g. [type="text"] ▸ Pseudo-classes/-elements, e.g. a:hover

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EXPENSIVE CSS PROPERTIES NTH-CHILD, FILTER, BOX-SHADOW

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INEXPENSIVE POSITION, SCALE, ROTATION AND OPACITY

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LAYOUT PAINT COMPOSITE

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CSS TRIGGERS HTTPS://CSSTRIGGERS.COM/

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COMPOSITE BE LIKE requestAnimationFrame

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SCSS TRICKS

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VARIBALES $cols: 12; $gutter: 20px; @for $col from 1 through $cols { .col-#{$col} { $pw: percentage($col/$cols); width: calc(#{$pw} - #{$gutter - $gutter / $col }); } }

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FUNCTIONS

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#{ $var and func() }

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background: inline-svg("");

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@function inline-svg($string) { @return url('data:image/svg+xml,#{url-encode($string)}'); }

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CONDITOIONALS

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$base-transition: 250ms all ease-in-out; $transitions: true; .#{$card}-details { background: #fff; @if ($transitions) { transition: $base-transition; } }

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& & &

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$card: card; .card { &-enclosed {} &.active, &:hover, &:focus {} }

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.card-enclosed {} .card .active, .card :hover, .card:focus {}

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SASS @extend AND MIXINS

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.error { border: 1px #f00; background-color: #fdd; &--serious { @extend .error; border-width: 3px; } }

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.error, .error--serious { border: 1px #f00; background-color: #fdd; } .error--serious { border-width: 3px; }

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@mixin reset-list { list-style: none; } nav ul { @include reset-list; li { display: inline-block; } }

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nav ul { list-style: none; } nav ul li { display: inline-block; }

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IE 9, 10, 11 DIE JANUARY 10TH?

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CSS VARABLES

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:root { --main-bg-color: coral; } #div1 { background-color: var(--main-bg-color); }

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SCOPING

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/* default color */ :root { --color: blue; } div { --color: green; } .myclass { --color: red; } /* applies the --color property at all the above levels */ * { color: var(--color); }

blue

green

red

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@supports

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@supports (display: grid) and (flex: 1) { /* your rules */ } @supports not (display: grid) or (flex: 1) { /* your rules */ }