CSS Grid matching heights

Question

I am having some issues with CSS grid (i think).

The left-hand side of my grid won't match the height on the other side. There always seems to be a gap at the bottom of the big image.

I need the grid all to be equal heights and 4/3 aspect ratio.

Any ideas? Thanks

body {
  padding: 40px;
}

* {
  margin: 0px;
  padding: 0px;
}

.grid-gallery {
  list-style: none;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  grid-template-rows: 1fr 1fr;
  gap: 1rem;
}

.grid-gallery-item:first-child {
  grid-row: span 2;
}

img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  aspect-ratio: 4 / 3;
}

<div class="grid-gallery">
  <div class="grid-gallery-item">
    <button>
      <img src="https://via.placeholder.com/400" />
    </button>
  </div>
  
   <div class="grid-gallery-item">
    <button>
      <img src="https://via.placeholder.com/400" />
    </button>
  </div>
  
   <div class="grid-gallery-item">
    <button>
      <img src="https://via.placeholder.com/400" />
    </button>
  </div>
  
   <div class="grid-gallery-item">
    <button>
      <img src="https://via.placeholder.com/400" />
    </button>
  </div>
  
   <div class="grid-gallery-item">
    <button>
      <img src="https://via.placeholder.com/400" />
    </button>
  </div>
</div>

Answer 1

Your buttons need to have the same size as the images

body {
  padding: 40px;
}

* {
  margin: 0px;
  padding: 0px;
}

.grid-gallery {
  list-style: none;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  grid-template-rows: 1fr 1fr;
  gap: 1rem;
}

.grid-gallery-item:first-child {
  grid-row: span 2;
}

button {
  width: 100%;
  height: 100%;
}

img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  aspect-ratio: 4 / 3;
}

<div class="grid-gallery">
  <div class="grid-gallery-item">
    <button>
      <img src="https://via.placeholder.com/400" />
    </button>
  </div>

  <div class="grid-gallery-item">
    <button>
      <img src="https://via.placeholder.com/400" />
    </button>
  </div>

  <div class="grid-gallery-item">
    <button>
      <img src="https://via.placeholder.com/400" />
    </button>
  </div>

  <div class="grid-gallery-item">
    <button>
      <img src="https://via.placeholder.com/400" />
    </button>
  </div>

  <div class="grid-gallery-item">
    <button>
      <img src="https://via.placeholder.com/400" />
    </button>
  </div>
</div>