JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="gallery">
    <div></div>
    <div></div>
    <div></div>
    <div></div>
  </div>
  <h2>Some Title</h2>
  <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.</p>
</div>

CSS

* {
  margin: 0;
}

.container {
  background-color: aqua;
  display: grid;
  padding: 1rem;
  grid-template-columns: 1fr 18rem; /* Create room for the gallery */
  grid-template-rows: repeat(2, min-content);
  grid-template-areas:
      'title gallery'
      'description gallery';
  grid-gap: 1rem;
  position: relative /* Create context for absolute positioning later */
}

.gallery {
  grid-area: gallery;
  display: grid;
  grid-template-columns: 8rem 8rem;
  grid-auto-rows: 8rem;
  grid-gap: 1rem;
  overflow-y: auto;
  position: absolute; /* Remove gallery from flow */
  top: 0; /* Align with container borders */
  right: 0;
  bottom: 0;
}

.gallery > * {
  background-color: magenta;
}

h2 {
  grid-area: title;
  background-color: white;
}

p {
  grid-area: description;
  background-color: lightgrey;
}