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HTML

              
                <aside style="display: none" id="js-banner" class="banner">
  <div class="banner__inner">
    This browser currently doesn't support Shared Element
    Transitions API. Use Chrome 104+ or Canary with
    <b>chrome://flags/#document-transition</b> enabled to view the
    example.
  </div>
</aside>
<h1>Calvin's super-awesome to-do list</h1>
<section class="grid">
  <article class="col">
    <h2>🤔 To-do</h2>
    <ul>
      <li id="card-1" style="--card-color: #b9fbc0">
        <div class="title">Watch cartoons</div>
        <div class="card-controls">
          <button onclick="moveCard(true)">👍</button>
          <button onclick="moveCard(false)">👎</button>
        </div>
      </li>
      <li id="card-2" style="--card-color: #ffcfd2">
        <div class="title">Play Calvinball</div>
        <div class="card-controls">
          <button onclick="moveCard(true)">👍</button>
          <button onclick="moveCard(false)">👎</button>
        </div>
      </li>
      <li id="card-3" style="--card-color: #98f5e1">
        <div class="title">Build a Transmogrifier</div>
        <div class="card-controls">
          <button onclick="moveCard(true)">👍</button>
          <button onclick="moveCard(false)">👎</button>
        </div>
      </li>
      <li id="card-4" style="--card-color: #cfbaf0">
        <div class="title">Pull a prank on Hobbes</div>
        <div class="card-controls">
          <button onclick="moveCard(true)">👍</button>
          <button onclick="moveCard(false)">👎</button>
        </div>
      </li>

      <li id="card-5" style="--card-color: #fbf8cc">
        <div class="title">Go on a treasure hunt</div>
        <div class="card-controls">
          <button onclick="moveCard(true)">👍</button>
          <button onclick="moveCard(false)">👎</button>
        </div>
      </li>
    </ul>
  </article>

  <article class="col col-complete">
    <h2>😊 Done!</h2>
    <ul id="js-list-done">
      <li style="--card-color: #8eecf5">Wake up early</li>
      <li style="--card-color: #f1c0e8">
        Have sugar bombs for breakfast
      </li>
    </ul>
  </article>

  <article class="col col-complete">
    <h2>😒 Won't-do</h2>
    <ul id="js-list-not-done">
      <li style="--card-color: #eaeaea">Clean my room</li>
      <li style="--card-color: #eaeaea">Go to sleep on time</li>
      <li style="--card-color: #eaeaea">Play with Susie</li>
    </ul>
  </article>
</section>
              
            
!

CSS

              
                @supports (page-transition-tag: none) {
  li {
    contain: paint;
  }
}

@supports not (page-transition-tag: none) {
    .banner {
        position: fixed;
        bottom: 0;
        left: 0;
        width: 100%;
        background-color: #fae588;
        text-align: center;
        z-index: 5;
    }

    .banner__inner {
        padding: 1rem 2rem;
        max-width: 720px;
        margin: 0 auto;
    }

    .banner {
        display: block !important;
    }
}

.card-moving {
  z-index: 2;
  position:relative;
}


:root {
    --font-body: "Albert Sans", sans-serif;
    --font-heading: "Indie Flower", cursive;
}

body {
    padding: 3rem 1rem;
    width: 1280px;
    margin: 0 auto;
    font-family: var(--font-body);
    display: flex;
    flex-direction: column;
}

h1,
h2 {
    font-family: var(--font-heading);
}

html,
body {
    min-height: 100%;
    background-color: #edf2fb;
}

.grid {
    display: flex;
    gap: 3rem;
    user-select: none;
    align-items: flex-start;
}

h1 {
    margin-bottom: 3rem;
    font-size: 5rem;
    text-align: center;
}

h2 {
    margin-bottom: 1rem;
    font-size: 3.5rem;
}

.col {
    background-color: #fff;
    flex-grow: 1;
    flex-basis: 33.33%;
    border-radius: 8px;
    padding: 2rem 2rem;
    box-shadow: 0 5px 10px 0 #aaa;
    align-items: flex-start;
}

ul {
    list-style: none;
    margin: 0;
    padding: 0;
}

li {
    background-color: var(--card-color);
    padding: 1rem;
    border-radius: 8px;
    margin-bottom: 2rem;
    font-weight: 700;
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    font-size: 21px;
    gap: 1rem;
}

li .title {
    flex-grow: 1;
    line-height: 1.25;
}

button {
    background: rgba(0, 0, 0, 0.15);
    border-radius: 100%;
    cursor: pointer;
    border-width: 0;
    display: flex;
    margin: 0;
    aspect-ratio: 1;
    align-items: center;
    justify-self: center;
}

button:hover {
    background: rgba(0, 0, 0, 0.25);
}

button:active {
    background: rgba(0, 0, 0, 0 0.3);
}

.card-controls {
    display: flex;
    gap: 0.5rem;
    font-size: 14px;
}

.card-moving .card-controls {
    visibility: hidden;
}


@media (prefers-reduced-motion) {
    ::page-transition-container(*),
    ::page-transition-outgoing-image(*),
    ::page-transition-incoming-image(*) {
        animation: none !important;
    }
}

/*
  1. Use a more-intuitive box-sizing model.
*/
*,
*::before,
*::after {
    box-sizing: border-box;
}
/*
    2. Remove default margin
  */
* {
    margin: 0;
}
/*
    3. Allow percentage-based heights in the application
  */
html,
body {
    height: 100%;
}
/*
    Typographic tweaks!
    4. Add accessible line-height
    5. Improve text rendering
  */
body {
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    font-family: Arial, Helvetica, sans-serif;
}
/*
    6. Improve media defaults
  */
img,
picture,
video,
canvas,
svg {
    display: block;
    max-width: 100%;
}
/*
    7. Remove built-in form typography styles
  */
input,
button,
textarea,
select {
    font: inherit;
}
/*
    8. Avoid text overflows
  */
p,
h1,
h2,
h3,
h4,
h5,
h6 {
    overflow-wrap: break-word;
}
              
            
!

JS

              
                // Assign unique page-transition-tag values to all task cards
const allCards = document.querySelectorAll(".col:not(.col-complete) li");
allCards.forEach(
  (c, index) => (c.style.pageTransitionTag = `card-${index + 1}`)
);

async function moveCard(isDone) {
  const card = this.window.event.target.closest("li");

  // Get the target list id
  const destination = document.getElementById(
    `js-list-${isDone ? "done" : "not-done"}`
  );

  // We'll use this class to hide the item controls while animation is running
  card.classList.add("card-moving");

  if (document.createDocumentTransition) {
    // Replace the item tag with active (moving) element tag
    card.style.pageTransitionTag = "card-active";

    const moveTransition = document.createDocumentTransition();

    // Run animation
    await moveTransition.start(() => destination.appendChild(card));

    // Remove the tag after animation ends
    card.style.pageTransitionTag = "none";
  } else {
    // Fallback
    destination.appendChild(card);
  }
}

              
            
!
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