.outer-container {
  display: flex;
}

<div class="outer-container">
  <div class="inner-container">
    <!-- 内层容器的内容 -->
  </div>
</div>

.inner-container {
  display: flex;
}

.outer-container {
  display: flex;
  flex-direction: row; /* 水平排列 */
  justify-content: center; /* 水平居中对齐 */
  align-items: center; /* 垂直居中对齐 */
}

.inner-container {
  display: flex;
  flex-direction: column; /* 垂直排列 */
  justify-content: flex-start; /* 顶部对齐 */
  align-items: flex-start; /* 左对齐 */
}