<div class="gallery">
  <div class="gallery__item">
    <div class="embed">
      <img src="https://source.unsplash.com/collection/582659/1" />
    </div>
  </div>
  <div class="gallery__item">
    <div class="embed">
      <img src="https://source.unsplash.com/collection/582659/2" />
    </div>
  </div>
  <div class="gallery__item">
    <div class="embed">
      <img src="https://source.unsplash.com/collection/582659/3" />
    </div>
  </div>
  <div class="gallery__item gallery__item--v-2">
    <div class="embed embed--1-2">
      <img src="https://source.unsplash.com/collection/582659/4" />
    </div>
  </div>
  <div class="gallery__item">
    <div class="embed">
      <img src="https://source.unsplash.com/collection/582659/5" />
    </div>
  </div>
  <div class="gallery__item gallery__item--h-2">
    <div class="embed embed--2-1">
      <img src="https://source.unsplash.com/collection/582659/6" />
    </div>
  </div>
  <div class="gallery__item gallery__item--v-2">
    <div class="embed embed--1-2">
      <img src="https://source.unsplash.com/collection/582659/7" />
    </div>
  </div>
  <div class="gallery__item gallery__item--h-2">
    <div class="embed embed--2-1">
      <img src="https://source.unsplash.com/collection/582659/8" />
    </div>
  </div>
  <div class="gallery__item gallery__item--v-2">
    <div class="embed embed--1-2">
      <img src="https://source.unsplash.com/collection/582659/9" />
    </div>
  </div>
  <div class="gallery__item gallery__item--h-2 gallery__item--v-2">
    <div class="embed">
      <img src="https://source.unsplash.com/collection/582659/10" />
    </div>
  </div>
  <div class="gallery__item">
    <div class="embed">
      <img src="https://source.unsplash.com/collection/582659/11" />
    </div>
  </div>
  <div class="gallery__item gallery__item--h-2 gallery__item--v-2">
    <div class="embed">
      <img src="https://source.unsplash.com/collection/582659/12" />
    </div>
  </div>
  <div class="gallery__item">
    <div class="embed">
      <img src="https://source.unsplash.com/collection/582659/13" />
    </div>
  </div>
  <div class="gallery__item gallery__item--h-2 gallery__item--v-3">
    <div class="embed embed--2-3">
      <img src="https://source.unsplash.com/collection/582659/14" />
    </div>
  </div>
  <div class="gallery__item gallery__item--h-2 gallery__item--v-2">
    <div class="embed">
      <img src="https://source.unsplash.com/collection/582659/15" />
    </div>
  </div>
  <div class="gallery__item gallery__item--v-2">
    <div class="embed embed--1-2">
      <img src="https://source.unsplash.com/collection/582659/16" />
    </div>
  </div>
  <div class="gallery__item">
    <div class="embed">
      <img src="https://source.unsplash.com/collection/582659/17" />
    </div>
  </div>
  <div class="gallery__item">
    <div class="embed">
      <img src="https://source.unsplash.com/collection/582659/18" />
    </div>
  </div>
  <div class="gallery__item">
    <div class="embed">
      <img src="https://source.unsplash.com/collection/582659/19" />
    </div>
  </div>
  <div class="gallery__item">
    <div class="embed">
      <img src="https://source.unsplash.com/collection/582659/20" />
    </div>
  </div>
</div>

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-block-size: 100vh;
  padding: 5vmin;
}

img {
  block-size: auto;
  max-inline-size: 100%;
  vertical-align: middle;
}

/* Embed */

.embed {
  overflow: hidden;
  padding-block-start: 100%;
  position: relative;
}

.embed--1-2 {
  padding-top: calc(100% / (1 / 2));
}

.embed--2-1 {
  padding-top: calc(100% / (2 / 1));
}

.embed--2-3 {
  padding-top: calc(100% / (2 / 3));
}

.embed > * {
  height: 100%;
  left: 0;
  object-fit: cover;
  padding: 0.25em;
  position: absolute;
  top: 0;
  width: 100%;
}

/* Gallery  */

.gallery {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  grid-template-rows: repeat(5, 1fr);
}

.gallery__item--h-2 {
  grid-column-end: span 2;
}

.gallery__item--h-3 {
  grid-column-end: span 3;
}

.gallery__item--v-2 {
  grid-row-end: span 2;
}

.gallery__item--v-3 {
  grid-row-end: span 3;
}