JSFiddle - React, Tailwind, and code Playground

HTML

<div class="ctnr">
  <header></header>
  <main>
    <div class="grid">
      <article class="c1">1</article>
      <article class="c2">2</article>
      <article class="c3">3</article>
      <article class="c4">4</article>
      <article class="c5">5</article>
      <article class="c6">6</article>
      <article class="c7">7</article>
    </div>
  </main>
  <footer></footer>
</div>

CSS

.ctnr{
  display: flex;
  /* display: block; */
  flex-flow: column;
  align-items: stretch;
}
header{ background: red; height: 2rem; }
main {
	min-width: 15rem; /* adjustment */
	height: 25rem;
	margin: auto;
	overflow: auto;
}

.grid{
  display: grid;
	height: 25rem;
  align-items: stretch;
  grid-template-areas: 
  "c1 c1 c1 c2 c3 c3 c3"
  "c4 c4 c4 c4 c3 c3 c3"
  "c4 c4 c4 c4 c5 c6 c6"
  "c4 c4 c4 c4 c7 c7 c7";
	grid-gap: 10px;
}
.grid article{
	cursor: pointer;
}
.grid article:nth-child(odd){
  background: yellow;
}
.grid article:nth-child(even){
  background: cyan;
}
.c1{ grid-area: c1; }
.c2{ grid-area: c2; }
.c3{ grid-area: c3; }
.c4{ grid-area: c4; }
.c5{ grid-area: c5; }
.c6{ grid-area: c6; }
.c7{ grid-area: c7; }