how to extend a grid code example

Example 1: css grid example

<!-- HTML code -->
<div class="wrapper">
  <div class="box">A</div><div class="box">B</div><div class="box">C</div>
  <div class="box">D</div><div class="box">E</div><div class="box">F</div>
</div>

<!-- Css code -->
<style>
.wrapper {
  display: grid;
  grid-template-columns: 100px 100px 100px;
  grid-gap: 10px;
  background-color: #fff;
  color: #444;
}
.box {
  background-color: #444;
  color: #fff;
  border-radius: 5px;
  padding: 20px;
  font-size: 150%;
}
</style>

Example 2: display grid

.container {
  display: grid | inline-grid;
}