<div class="container">
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
</div>

body {
    padding: 2rem;
    background-color: whitesmoke;
}

.item {
    background-color: skyblue;
    border-radius: 5px;
    height: 180px;
    width: 100%;
}

.container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    grid-gap: 1rem;
}