<div class="container">
  <div class="item">1</div>
  <div class="item">2</div>
  <div class="item">3</div>
</div>

<div class="container column">
  <div class="item">1</div>
  <div class="item">2</div>
  <div class="item">3</div>
</div>

body {
  padding: 20px;
  font: 1em Helvetica Neue, Helvetica, Arial, sans-serif;
}

* {box-sizing: border-box;}

p {
  margin: 0 0 1em 0;
}

.container {
  width: 500px;
  border: 5px solid rgb(111,41,97);
  border-radius: .5em;
  padding: 10px;
  display: flex;
  justify-content: space-between;
  margin: 1em;
}

.column {
  flex-direction: column;
  height: 400px;
}

.item {
  width: 100px;
  height: 100px;
  padding: 10px;
  background-color: rgba(111,41,97,.3);
  border: 2px solid rgba(111,41,97,.5);
}