<div class="grid">
  <div>Item One</div>
  <div>Item Two</div>
  <div>Item Three</div>
  <div>Item Four</div>
</div>

body {
  padding: 50px;
  font: 1em Helvetica Neue, Helvetica, Arial, sans-serif;
}

.grid {
  border: 5px solid rgb(111,41,97);
  display: grid;
  grid-template-columns: repeat(auto-fill, 200px);
  width: 500px;
}

.grid > * {
  background-color: rgba(111,41,97,.4);
  border-radius: 5px;
  padding: 10px;
}