溢出自动不适用于弹性容器

Question

我正在尝试制作一个简单的聊天窗口，其中消息锚定在窗口的右侧和底部。我希望聊天窗口在消息溢出窗口时滚动。

我正在使用 flexbox 来定位消息，并给窗口一个overflow-y: auto;. 由于某种原因，我无法理解这不起作用。如果我从窗口中删除了 flex 定位，滚动会按预期正常工作。为什么 flexbox 会改变滚动行为？

这是一个显示问题的非常简单的代码笔：https ://codepen.io/skypod/pen/OdavbR

.chat-window {
  background-color: grey;
  width: 400px;
  height: 400px;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  align-items: flex-end;
  overflow-y: auto;
}

.message {
  background-color: blue;
  color: white;
  padding: 0.5rem;
  margin: 0.25rem;
}

<div class="chat-window">
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
  <div class="message">text</div>
</div>

Answer 1

删除justify-content: flex-end并添加flex-direction: column-reverse而不是列方向。现在为s添加一个包装器message- 请参见下面的演示：

.chat-window {
  background-color: grey;
  width: 400px;
  height: 400px;
  display: flex;
  flex-direction: column-reverse; /* CHANGED */
  /*justify-content: flex-end;*/
  align-items: flex-end;
  overflow-y: auto;
}

.message {
  background-color: blue;
  color: white;
  padding: 0.5rem;
  margin: 0.25rem;
}

<div class="chat-window">
  <div class="message-wrapper">
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
    <div class="message">text</div>
  <div>
</div>