How do I make the first grid item span 100%?

.footer-inner {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
}

.footer-inner div {
  border: 1px solid grey;
  text-align: center;
}

.footer-inner :first-child {
  grid-column: 1 / -1;
}

<div class="footer-inner">
  <div>One</div>
  <div>Two</div>
  <div>Three</div>
  <div>Four</div>
</div>