将两个div并排垂直居中对齐

.parent-container {
  display: flex;
  justify-content: center;
  align-items: center;
}

<div class="parent-container">
  <div class="child-div"></div>
  <div class="child-div"></div>
</div>

.child-div {
  width: 200px;
  height: 200px;
  background-color: #ccc;
}