<div class="box">
  <div class="first-item">
    <h1> 1 </h1>
  </div>
  <div class="second-item">
    <h1> 2</h1>
  </div>
  <div class="third-item">
    <h1> 3</h1>
  </div>
  <div class="fourth-item">
    <h1>4 </h1>
  </div>
</div>

.box{
  display: flex;
}