Stop writing CSS
like it's 2015.

Animation

Beginner

Reduced motion without JavaScript detection

Old const mq = window.matchMedia('(prefers-reduced-motion)');
if (mq.matches) el.style.animation = 'none';

Modern @media (prefers-reduced-motion: reduce) {
  * { animation-duration: 0.01ms !important; }
}

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Color

Intermediate

Perceptually uniform colors with oklch

Old --brand: #4f46e5;
--brand-light: #818cf8;
--brand-dark: #3730a3;
/* guess-and-check each shade */

Modern --brand: oklch(0.55 0.2 264);
--brand-light: oklch(0.75 0.2 264);
--brand-dark: oklch(0.35 0.2 264);
/* only L changes, same perceived hue */

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Workflow

Beginner

CSS feature detection without JavaScript

Old // Modernizr or manual check
if (CSS.supports('display', 'grid')) {
  el.classList.add('grid');
}

Modern @supports (display: grid) {
  .layout { display: grid; }
}
/* no JS required */

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Color

Intermediate

Frosted glass effect without opacity hacks

Old .card::before { content: '';
  background-image: url(bg.jpg);
  filter: blur(12px);
  z-index: -1; }

Modern .glass {
  backdrop-filter: blur(12px);
  background: rgba(255,255,255,.1);
}

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Layout

Beginner

Exclusive accordions without JavaScript

Old // JS: close all, open clicked
details.forEach(d => d.open = false);
this.open = true;

Modern <details name="faq">...</details>
<details name="faq">...</details>
/* browser closes others */

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Animation

Intermediate

Custom easing curves without cubic-bezier guessing

Old /* JS animation library */
anime({ targets: el,
  easing: 'easeOutBounce' });

Modern transition: transform 1s
  linear(0, 1.2, 0.9, 1.05, 1);
/* bounce — no JS needed */

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Layout

Beginner

Preventing layout shift from scrollbar appearance

Old body { overflow-y: scroll; }
/* or hardcode the scrollbar width */
body { padding-right: 17px; }

Modern body {
  scrollbar-gutter: stable;
}
/* scrollbar space always reserved */

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Layout

Beginner

Media query ranges without min-width and max-width

Old @media (min-width: 600px)
         and (max-width: 1200px) {
  /* styles */
}

Modern @media (600px <= width <= 1200px) {
  /* styles */
}

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Layout

Beginner

Preventing scroll chaining without JavaScript

Old // JS: block page scroll when inside modal
modal.addEventListener('wheel', e =>
  e.preventDefault(), { passive: false })

Modern .modal-content {
  overflow-y: auto;
  overscroll-behavior: contain;
}
/* page stays still */

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Layout

Beginner

Responsive images without the background-image hack

Old .card-image {
  background-image: url(...);
  background-size: cover;
  background-position: center;
}

Modern img {
  object-fit: cover;
  width: 100%;
  height: 200px;
}

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Layout

Beginner

Scrollbar styling without -webkit- pseudo-elements

Old /* webkit only */
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-thumb { background: #888; }

Modern * {
  scrollbar-width: thin;
  scrollbar-color: #888 transparent;
}

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Layout

Beginner

Mobile viewport height without the 100vh hack

Old .hero {
  height: 100vh;
}
/* overflows on mobile */

Modern .hero {
  height: 100dvh;
}
/* adapts to browser chrome */

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Selector

Beginner

Form validation styles without JavaScript

Old // JS: add .touched on blur
el.addEventListener('blur', () =>
  el.classList.add('touched'))
/* .touched:invalid { color: red } */

Modern input:user-invalid {
  border-color: red;
}
input:user-valid {
  border-color: green;
}

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Layout

Beginner

Auto-growing textarea without JavaScript

Old // JS: resize on every keystroke
el.addEventListener('input', () => {
  el.style.height = 'auto';
  el.style.height = el.scrollHeight + 'px'; })

Modern textarea {
  field-sizing: content;
  min-height: 3lh;
}
/* grows with content, no JS */

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Animation

Beginner

Smooth height auto animations without JavaScript

Old // measure, set px, then snap to auto
el.style.height = el.scrollHeight + 'px';
el.addEventListener('transitionend', ...)

Modern :root { interpolate-size: allow-keywords; }
.accordion { height: 0; overflow: hidden;
  transition: height .3s ease; }
.accordion.open { height: auto; }

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Workflow

Advanced

Range style queries without multiple blocks

Old /* Multiple style() blocks */
@container style(--p: 51%) {}
@container style(--p: 52%) {}
/* ...for each value */

Modern @container style(
  --progress > 50%
) {
  .bar { ... }
}

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Animation

Intermediate

Sticky & snapped element styling without JavaScript

Old window.addEventListener(
  'scroll', () => {
    /* check position */
});

Modern @container scroll-state(
  stuck: top
) {
  .header { ... }
}

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Workflow

Intermediate

Typed attribute values without JavaScript

Old // JS reading dataset
el.style.width =
  el.dataset.pct + '%';

Modern .bar {
  width: attr(
    data-pct type(<percentage>)
  );
}

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Workflow

Intermediate

Inline conditional styles without JavaScript

Old // JavaScript toggling
el.classList.toggle(
  'primary', isPrimary
);

Modern .btn {
  background: if(
    style(--variant: primary):
      blue; else: gray
  );
}

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Workflow

Intermediate

Reusable CSS logic without Sass mixins

Old // Sass function
@function fluid($min, $max) {
  @return clamp(...);
}

Modern @function --fluid(
  --min, --max
) {
  @return clamp(...);
}

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Layout

Beginner

Corner shapes beyond rounded borders

Old .card {
  clip-path: polygon(
    ... /* 20+ points */
  );
}

Modern .card {
  border-radius: 2em;
  corner-shape: squircle;
}

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Animation

Advanced

Responsive clip paths without SVG

Old .shape {
  clip-path: path(
    'M0 200 L100 0...'
  );
}

Modern .shape {
  clip-path: shape(
    from 0% 100%, ...
  );
}

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Selector

Intermediate

Scroll spy without IntersectionObserver

Old const observer = new
  IntersectionObserver(cb);
/* 15+ lines of JS */

Modern nav a:target-current {
  color: var(--accent);
}

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Layout

Beginner

Filling available space without calc workarounds

Old .full {
  width: calc(100% - 40px);
  /* or width: 100% and overflow */
}

Modern .full {
  width: stretch;
}
/* fills container, keeps margins */

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Animation

Intermediate

Staggered animations without nth-child hacks

Old li:nth-child(1) { --i: 0; }
li:nth-child(2) { --i: 1; }
li:nth-child(3) { --i: 2; }
/* repeat for every item… */

Modern li {
  transition-delay:
    calc(0.1s * (sibling-index() - 1));
}

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Layout

Advanced

Carousel navigation without a JavaScript library

Old // Swiper.js or Slick carousel
new Swiper('.carousel', {
  navigation: { /* … */ },
  pagination: { /* … */ },
});

Modern .carousel::scroll-button(right) {
  content: "➡";
}
.carousel li::scroll-marker {
  content: '';
}

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Typography

Beginner

Vertical text centering without padding hacks

Old .btn {
  padding: 10px 20px;
  /* looks off-center, tweak top/bottom */
  padding-top: 8px; /* hack */
}

Modern h1, button {
  text-box: trim-both cap alphabetic;
}
/* true optical centering */

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Layout

Intermediate

Hover tooltips without JavaScript events

Old // JS: mouseenter + mouseleave
btn.addEventListener('mouseenter',
  () => showTooltip())
/* + focus, blur, positioning */

Modern <button interestfor="tip">Hover me</button>
<div id="tip" popover=hint>
  Tooltip content
</div>

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Layout

Beginner

Modal controls without onclick handlers

Old <button onclick="
  document.querySelector('#dlg')
  .showModal()">Open</button>

Modern <button commandfor="dlg"
  command="show-modal">Open</button>
<dialog id="dlg">...</dialog>

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Layout

Beginner

Dialog light dismiss without click-outside listeners

Old // JS: listen for click on ::backdrop
dialog.addEventListener('click',
  (e) => { /* check bounds */ })

Modern <dialog closedby="any">
  Click outside to close
</dialog>
/* no JS listeners */

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Layout

Intermediate

Customizable selects without a JavaScript library

Old // Select2 or Choices.js
new Choices('#my-select');
/* rebuilds entire DOM */

Modern select,
select ::picker(select) {
  appearance: base-select;
}

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Color

Intermediate

Vivid colors beyond sRGB

Old .hero {
  color: rgb(200, 80, 50);
}
/* sRGB only, washed on P3 */

Modern .hero {
  color: oklch(0.7 0.25 29);
}
/* or color(display-p3 1 0.2 0.1) */

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Color

Advanced

Color variants without Sass functions

Old /* Sass: lighten($brand, 20%), darken($brand, 10%) */
.btn { background: #e0e0e0; }

Modern .btn {
  background: oklch(from var(--brand) calc(l + 0.2) c h);
}

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Typography

Beginner

Multiline text truncation without JavaScript

Old /* JS: slice text by chars/words, add "..." */
.card-title { overflow: hidden; }

Modern .card-title {
  display: -webkit-box;
  -webkit-line-clamp: 3;
  line-clamp: 3;
}

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Typography

Beginner

Drop caps without float hacks

Old .drop-cap::first-letter {
  float: left;
  font-size: 3em; line-height: 1;
}

Modern .drop-cap::first-letter {
  initial-letter: 3;
}

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Layout

Beginner

Positioning shorthand without four properties

Old .overlay {
  top: 0; right: 0;
  bottom: 0; left: 0;
}

Modern .overlay {
  position: absolute;
  inset: 0;
}

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Workflow

Intermediate

Lazy rendering without IntersectionObserver

Old // JS IntersectionObserver
new IntersectionObserver(
  (entries) => { /* render */ }
).observe(el);

Modern .section {
  content-visibility: auto;
  contain-intrinsic-size: auto 500px;
}

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Layout

Beginner

Dropdown menus without JavaScript toggles

Old .menu { display: none; }
.menu.open { display: block; }
/* + JS: click, clickOutside, ESC, aria */

Modern button[popovertarget=menu] { }
#menu[popover] {
  position: absolute;
}

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Layout

Advanced

Tooltip positioning without JavaScript

Old /* Popper.js / Floating UI: compute rect,
position: fixed, update on scroll */
.tooltip { position: fixed; }

Modern .trigger { anchor-name: --tip; }
.tooltip {
  position-anchor: --tip;
  top: anchor(bottom);
}

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Workflow

Advanced

Scoped styles without BEM naming

Old // BEM: .card__title, .card__body
.card__title { … }
.card__body { … }
// or CSS Modules / styled-components */

Modern @scope (.card) {
  .title { font-size: 1.25rem; }
  .body { color: #444; }
}
/* .title only inside .card */

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Workflow

Advanced

Typed custom properties without JavaScript

Old // --hue was a string, no animation
:root { --hue: 0; }
hsl(var(--hue), …) /* no interpolation */

Modern @property --hue {
  syntax: "<angle>";
  inherits: false;
  initial-value: 0deg;
}
/* animatable, validated */

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Animation

Beginner

Independent transforms without the shorthand

Old .icon { transform: translateX(10px) rotate(45deg) scale(1.2); }
/* change one = rewrite all */

Modern .icon {
  translate: 10px 0;
  rotate: 45deg;
  scale: 1.2;
}
/* animate any one without touching the rest */

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Animation

Intermediate

Animating display none without workarounds

Old // wait for transitionend then display:none
el.addEventListener('transitionend', …)
visibility + opacity + pointer-events

Modern .panel { transition: opacity .2s, overlay .2s;
  transition-behavior: allow-discrete; }
.panel.hidden { opacity: 0; display: none; }
/* no JS wait or visibility hack */

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Animation

Intermediate

Entry animations without JavaScript timing

Old // add class after paint
requestAnimationFrame(() => {
  el.classList.add('visible');
});

Modern .card { transition: opacity .3s, transform .3s; }
.card { @starting-style { opacity: 0; transform: translateY(10px); } }
/* no rAF/setTimeout */

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Animation

Advanced

Page transitions without a framework

Old // Barba.js or React Transition Group
Barba.init({ … })
transition hooks + duration state

Modern document.startViewTransition(() => updateDOM());
.hero { view-transition-name: hero; }
/* no Barba, no React TG */

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Layout

Intermediate

Scroll snapping without a carousel library

Old // Slick, Swiper, or scroll/touch JS
$('.carousel').slick({ … })
touchstart / scroll handlers

Modern .carousel { scroll-snap-type: x mandatory; }
.carousel > * { scroll-snap-align: start; }
/* no lib, no touch handlers */

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Typography

Beginner

Balanced headlines without manual line breaks

Old // manual <br> or Balance-Text.js
h1 { text-align: center; }
.balance-text /* JS lib */

Modern h1, h2 {
  text-wrap: balance;
}
/* no br or JS */

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Typography

Beginner

Font loading without invisible text

Old @font-face { ... }
/* Default: invisible text until load */

Modern @font-face {
  font-family: "MyFont";
  font-display: swap;
}

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Typography

Intermediate

Multiple font weights without multiple files

Old @font-face { font-weight: 400; }
@font-face { font-weight: 700; }
/* 4+ files */

Modern @font-face {
  font-family: "MyVar";
  src: url("MyVar.woff2");
  font-weight: 100 900;
}

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Workflow

Beginner

Dark mode defaults without extra CSS

Old @media (prefers-color-scheme: dark) {
  input, select, textarea { ... }
}

Modern :root {
  color-scheme: light dark;
}

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Color

Intermediate

Dark mode colors without duplicating values

Old @media (prefers-color-scheme: dark) {
  color: #eee;
}

Modern color: light-dark(#111, #eee);
color-scheme: light dark;

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Selector

Intermediate

Low-specificity resets without complicated selectors

Old .reset ul, .reset ol { ... }
/* or (0,0,1) specificity, still wins */

Modern :where(ul, ol) {
  margin: 0;
  padding-inline-start: 1.5rem;
}

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Layout

Intermediate

Direction-aware layouts without left and right

Old margin-left: 1rem;
padding-right: 1rem;
[dir="rtl"] .box { margin-right: ... }

Modern margin-inline-start: 1rem;
padding-inline-end: 1rem;
border-block-start: 1px solid;

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Layout

Beginner

Naming grid areas without line numbers

Old float: left; /* clearfix, margins */
grid-column: 1 / 3;
grid-row: 2;

Modern .layout {
  display: grid;
  grid-template-areas: "header header" "sidebar main" "footer footer";
}

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Layout

Advanced

Aligning nested grids without duplicating tracks

Old .child-grid {
  grid-template-columns: 1fr 1fr 1fr;
/* duplicate parent tracks */
}

Modern .child-grid {
  display: grid;
  grid-template-columns: subgrid;
}

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Layout

Intermediate

Modal dialogs without a JavaScript library

Old .overlay { position: fixed; z-index: 999; }
/* + JS: open/close, ESC, focus trap */

Modern dialog {
  padding: 1rem;
}
dialog::backdrop { background: rgb(0 0 0 / .5); }

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Color

Beginner

Styling form controls without rebuilding them

Old appearance: none;
// + 20+ lines of custom box/border/background

Modern input[type="checkbox"],
input[type="radio"] {
  accent-color: #7c3aed;
}

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Selector

Beginner

Grouping selectors without repetition

Old .card h1, .card h2, .card h3, .card h4 {
  margin-bottom: 0.5em;
}

Modern .card :is(h1, h2, h3, h4) {
  margin-bottom: 0.5em;
}

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Selector

Beginner

Focus styles without annoying mouse users

Old :focus { outline: 2px solid blue; }
// Shows on mouse click too, or people remove it (a11y fail)

Modern :focus-visible {
  outline: 2px solid var(--focus-color);
}

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Workflow

Intermediate

Controlling specificity without !important

Old .card .title { ... }
.page .card .title { ... }
.page .card .title.special { color: red !important; }

Modern @layer base, components, utilities;
@layer utilities { .mt-4 { margin-top: 1rem; } }

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Workflow

Beginner

Theme variables without a preprocessor

Old // Sass: $primary: #7c3aed;
// Compiles to static #7c3aed
.btn { background: $primary; }

Modern :root {
  --primary: #7c3aed;
}
.btn { background: var(--primary); }

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Typography

Intermediate

Fluid typography without media queries

Old h1 { font-size: 1rem; }
@media (min-width: 600px) { h1 { font-size: 1.5rem; } }
@media (min-width: 900px) { h1 { font-size: 2rem; } }

Modern h1 {
  font-size: clamp(1rem, 2.5vw, 2rem);
}

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Layout

Beginner

Spacing elements without margin hacks

Old .grid > * { margin-right: 16px; }
.grid > *:last-child { margin-right: 0; }

Modern .grid {
  display: flex;
  gap: 16px;
}

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Layout

Beginner

Aspect ratios without the padding hack

Old .wrapper { padding-top: 56.25%; position: relative; }
.inner { position: absolute; inset: 0; }

Modern .video-wrapper {
  aspect-ratio: 16 / 9;
}

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Layout

Beginner

Sticky headers without JavaScript scroll listeners

Old // JS: scroll listener + getBoundingClientRect
// then add/remove .fixed class
.header.fixed { position: fixed; }

Modern .header {
  position: sticky;
  top: 0;
}

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Animation

Advanced

Scroll-linked animations without a library

Old // JS + IntersectionObserver
observer.observe(el)
el.style.opacity = …

Modern animation-timeline: view();
animation-range: entry;
/* pure CSS, GPU-accelerated */

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Workflow

Beginner

Nesting selectors without Sass or Less

Old // requires Sass compiler
.nav {
  & a { color: #888; }
}

Modern .nav {
  & a { color: #888; }
}
/* plain .css, no build */

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Layout

Intermediate

Responsive components without media queries

Old @media (max-width: 768px) {
  .card { … }
}
/* viewport, not container */

Modern @container (width < 400px) {
  .card { flex-direction: column; }
}

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Colors

Intermediate

Mixing colors without a preprocessor

Old // Sass required
$blend: mix(
  $blue, $pink, 60%);

Modern background: color-mix(
  in oklch, #3b82f6,
  #ec4899);

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Selectors

Intermediate

Selecting parent elements without JavaScript

Old // JavaScript required
el.closest('.parent')
  .classList.add(…)

Modern .card:has(img) {
  grid-template: auto 1fr;
}

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Layout

Beginner

Centering elements without the transform hack

Old position: absolute;
top: 50%; left: 50%;
transform: translate(-50%,-50%);

Modern .parent {
  display: grid;
  place-items: center;
}

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