Flex Example

HTML

<div class="container">
  <div>Div 1</div>
  <div>Div 2</div>
  <div>Div 3</div>
  <div>Div 4</div>
</div>

CSS

.container {
  padding: 20px;
  background: white;
  display: flex;
  flex-wrap: wrap;
}

.container > div {
  border: 1px solid black;
  background: #ececec;
  margin: 5px;
  width: calc(100% / 4);
  padding: 10px;
  flex-direction: column;
}