Pen Settings

HTML

CSS

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URLs added here will be added as <link>s in order, and before the CSS in the editor. You can use the CSS from another Pen by using its URL and the proper URL extension.

+ add another resource

JavaScript

Babel includes JSX processing.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

+ add another resource

Packages

Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.

Behavior

Auto Save

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.

HTML

              
                <header class="wrapper flow">
  <h1>50/50 flexbox layout</h1>
  <form id="size-form">
    <div class="cluster">
      <label for="size">Minimum size of each side:</label>
      <input type="text" id="size" name="size" value="250px" />
      <button type="submit">Update</button>
    </div>
  </form>

  <ul>
    <li>Card width: <span class="tnum" id="card-width"></span>px</li>
    <li>Side width: <span class="tnum" id="side-width"></span>px</li>
  </ul>
</header>

<main class="wrapper">
  <article class="card fifty-fifty">
    <section class="poster">
      <img src='https://images.unsplash.com/photo-1516370873344-fb7c61054fa9?crop=entropy&cs=tinysrgb&fit=max&fm=jpg&ixid=M3wzMjM4NDZ8MHwxfHJhbmRvbXx8fHx8fHx8fDE3MDc5MjA5MTF8&ixlib=rb-4.0.3&q=80&w=600' alt='Two people in bathing suits holding surfboards approach the ocean shoreline. One person holds their hand high in the sky.'>
    </section>
    <section class="content flow">
      <h2>Catch some waves</h2>
      <p>Enim nemo, exercitationem ullam voluptatum vero assumenda qui repellendus dolore.</p>
    </section>
  </article>

  <article class="card fifty-fifty">
    <section class="poster">
      <img src='https://images.unsplash.com/photo-1559339352-11d035aa65de?crop=entropy&cs=tinysrgb&fit=max&fm=jpg&ixid=M3wzMjM4NDZ8MHwxfHJhbmRvbXx8fHx8fHx8fDE3MDc5MjU4MTh8&ixlib=rb-4.0.3&q=80&w=600' alt='Beautiful outdoor patio dining area with the ocean and mountain in the background'>
    </section>
    <section class="content flow">
      <h2>Stay for the views</h2>
      <p>Lorem ipsum dolor, sit amet consectetur adipisicing elit. Officia illo voluptatibus.</p>
    </section>
  </article>
</main>
              
            
!

CSS

              
                @import url("https://fonts.googleapis.com/css2?family=Inter:wght@100..900&display=swap");

:root {
  --text-1: #f8fafc;
  --text-2: #cbd5e1;
  --surface-1: #020617;
  --surface-2: #0f172a;
  --surface-3: #1e293b;
  --surface-4: #334155;
  --button-surface: #1d4ed8;
  --gradient: linear-gradient(
    to bottom,
    hsla(0 0% 0% / 0) 0%,
    hsla(0 0% 100% / 0.065) 100%
  );
}

.fifty-fifty {
  display: flex;
  flex-wrap: wrap;
}

.fifty-fifty > * {
  flex-grow: 1;
  flex-basis: var(--min-inline-size, 250px);
}

.card {
  overflow: hidden;
  width: 100%;
  border-radius: 0.5rem;
  background-image: var(--gradient);
  box-shadow: inset 0 0 0 1px var(--surface-3);
}

.card p {
  color: var(--text-2);
}

.card img {
  aspect-ratio: 3 / 2;
  width: 100%;
  height: 100%;
  vertical-align: bottom;
  object-fit: cover;
}

.content {
  padding: 2rem;
  background-image: var(--surface-gradient);
}

.flow > * + * {
  margin-top: 1rem;
}

.wrapper {
  width: min(40rem, 100%);
  margin-inline: auto;
}

.cluster {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.2rem 0.5rem;
}

label {
  display: block;
}

.tnum {
  --_offset: 0.04em;

  padding-inline: var(--_offset);
  letter-spacing: calc(var(--_offset) * -1);
  font-variant-numeric: tabular-nums;
  font-weight: 600;
}

:where(input, button) {
  font: inherit;
  color: inherit;
  padding: 0.25rem 0.5rem;
  border: 1px solid var(--surface-4);
  background-color: var(--surface-2);
  border-radius: 0.15rem;
}

input[id="size"] {
  inline-size: 5em;
}

button {
  padding-inline: 0.75rem;
  border-color: var(--button-surface);
  background-color: var(--button-surface);
  background-image: var(--gradient);
}

button:active {
  translate: 0 1px;
}

* {
  box-sizing: border-box;
}

ul {
  padding-inline-start: 1em;
}

:where(h2, p) {
  margin: 0;
}

:where(h1, h2) {
  font-weight: 600;
  letter-spacing: -0.015em;
  line-height: normal;
}

h1 {
  font-size: 1.8rem;
}

h2 {
  font-size: 1.5rem;
}

a {
  color: #38bdf8;
}

header {
  margin-block-end: 2rem;
}

main {
  display: grid;
  gap: 1rem;
  grid-auto-rows: 1fr;
}

body {
  margin: 0;
  margin-block-end: 4rem;
  padding: 2rem;
  font-family: "Inter", sans-serif;
  color: var(--text-1);
  line-height: 1.5;
  background-color: var(--surface-1);
}

              
            
!

JS

              
                let root = document.documentElement;
let form = document.getElementById("size-form");
let submitBtn = form.querySelector("button");
let sizeInput = document.getElementById("size");
let cards = document.querySelectorAll(".card");
let card = cards[0];
let side = card.children[0];
let cardWidthValue = document.getElementById("card-width");
let sideWidthValue = document.getElementById("side-width");

function reportSizes() {
  cardWidthValue.textContent = card.clientWidth;
  sideWidthValue.textContent = side.clientWidth;
}

function handleSubmit(e) {
  e.preventDefault();

  let duration = 400;
  let keyframes = {
    backgroundColor: ["var(--surface-3)", "var(--surface-3)"],
    offset: [0.1, 0.4],
    easing: "ease-out"
  };

  root.style.setProperty("--min-inline-size", sizeInput.value);

  sizeInput.animate(keyframes, duration);

  for (let card of cards) {
    card.animate(keyframes, duration);
  }

  reportSizes();
}

window.addEventListener("resize", reportSizes);
form.addEventListener("submit", handleSubmit);

reportSizes();

              
            
!
999px

Console