div flex example

HTML

<div class="parent">
  <div class="sub-parent">
  <div class="child-1 child">
    child-1
  </div>
  <div class="child-2 child">
    child-2
  </div>
  </div>
  <div class="sub-parent">
  <div class="child-3">
    child-3
  </div>
  </div>
</div>

CSS

.parent {
  height: 50px;
  width: 100%;
  border: 1px solid red;
  display: flex;
  flex-direction: row;
  justify-content: space-between;
}

.child-1,
.child-2,
.child-3 {
  margin: 2px 1px;
  padding: 2px;
  border: 1px solid blue;
  display:flex;
}
.sub-parent {
  display: flex;
  flex-direction: row;
  justify-content: space-between;
}
.child-1 {}

.child-2 {}

.child-3 {}