JSFiddle - React, Tailwind, and code Playground

HTML

<div id="grid">
  <div id="item1" class="item"></div>
  <div id="item2" class="item"></div>
</div>

CSS

#grid {
  display: grid;
  position: relative;
  grid-template-columns: 100px 100px;
  grid-template-rows: minmax(auto, 0);
  align-items: baseline;
  height: 100px;
  width: 200px;
  border: solid;
  line-height: 0;
}
#grid::before {
  content: '';
  position: absolute;
  z-index: -1;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  background: cyan;
  grid-row: 1 / 2;
  grid-column: 1 / 3;
}
#item1 {
  padding-bottom: 100px;
  background: yellow;
}
#item2 {
  background: magenta;
  padding-top: 100px;
}
.item::before {
  content: ' ';
  display: inline-block;
  vertical-align: top;
}