<p>Check <a href="https://www.matuzo.at/blog/2023/100daysof-day97/">this post</a> for more details</p>

<button class="js-button">Animate</button>

<div class="grid js-grid">
  <div class="item">
    <h2>Element 1</h2>
  </div>
  <div class="item">
    <h2>Element 2</h2>
  </div>
  <div class="item">
    <h2>Element 3</h2>
  </div>
  <div class="item">
    <h2>Element 4</h2>
  </div>
  <div class="item">
    <h2>Element 5</h2>
  </div>
  <div class="item">
    <h2>Element 6</h2>
  </div>  
  <div class="item">
    <h2>Element 7</h2>
  </div>
  <div class="item">
    <h2>Element 8</h2>
  </div>
  <div class="item">
    <h2>Element 9</h2>
  </div>  
  <div class="item">
    <h2>Element 10</h2>
  </div>
  <div class="item">
    <h2>Element 11</h2>
  </div>
  <div class="item">
    <h2>Element 12</h2>
  </div>
</div>
html {
  overscroll-beahavior: contain;
}

.grid {
  --col: 9.5rem;
  --row: 8rem;
  --gap: 2rem;

  display: grid;
  grid-template-columns: repeat(3, var(--col));
  grid-template-rows: repeat(4, var(--row));
  grid-gap: var(--gap);
}

.grid--full {
  --col: 30%;
  --row: 4rem;
  --gap: 1rem;
}

@media (prefers-reduced-motion: no-preference) {
  .grid {
    transition: all 1s;
  }
}

button {
  background-color: #123456;
  color: #ffffff;
  margin: 2rem 0;
  padding: 1.4rem;
  border: none;
  border-radius: 5px;
  text-transform: uppercase;
  font-size: 1.2rem;
}

button:focus-visible {
  outline: 4px solid #123456;
  outline-offset: 4px;
}

dt {
  font-weight: bold;
  margin-bottom: 0.5rem;
}
document.querySelector('.js-button').addEventListener('click', function() {
  document.querySelector('.js-grid').classList.toggle('grid--full')
})

External CSS

  1. https://codepen.io/matuzo/pen/vmpaWe.css

External JavaScript

This Pen doesn't use any external JavaScript resources.