I have a flexbox header that contains two child flex items. These flex items in turn have their own children.

Is there a way to override the vertical alignment of the flex items so that their children are aligned at the bottom?

```css
div.flexbox {
  display: flex;
  align-items: stretch; /* cross axis */
  justify-content: space-between; /* main axis */
  flex-flow: row wrap;
  border-bottom: 1px solid #ddd;
  min-height: 100px;
}

.item-1, .item-2 {
  padding: 10px;
}

.item-1 {
  width: 30%;
  position: relative;
}

.item-2 {
  width: 60%;
}
```

```html
<div class="flexbox">
  <div class="item-1">
    <span>I want to be aligned at the bottom of item-1</span>
  </div>

  <div class="item-2">
    <span>I want to be aligned at the bottom of item-2</span>
  </div>
</div>
```