<div class="container clearfix">
  <div class="item float--left">1</div>
  <div class="item float--left">2</div>
  <div class="item float--right">3</div>
  <div class="item float--right">4</div>
</div>
.clearfix::after {
  content: '';
  display: block;
  clear: both;
}

.float--left {
  float: left;
}

.float--right {
  float: right;
}

.container {
  border: 4px solid;
}

.container .item {
  border-radius: 10px;
  width: 100px;
  height: 100px;
  background-color: royalblue;
  font-size: 40px;
  margin: 10px;
}

External CSS

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External JavaScript

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