如何让CSS Grid布局中溢出内容实现滚动？

我正在开发一个HTML/CSS项目，采用3列Grid布局，左侧列包含类终端界面，分为输出区和输入区。输出区（output-buffer）中的文本段落经常超出可用垂直空间。我的需求是当内容无法容纳时，output-buffer容器显示滚动条，但实际情况是容器会自动扩展以容纳多余内容。我已尝试为output-buffer设置overflow: auto;和height: 100%;，但未达预期，仅水平方向在内容过宽时能正常显示滚动条（缩小浏览器窗口宽度可观察）。请问如何修改CSS，让output-buffer在内容溢出时可滚动且不扩展尺寸？

以下是简化版代码：

<!DOCTYPE html>
<html>

<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">

  <title>WebSocket Game Client</title>

</head>

<style>
  html,
  body {
    height: 100vh;
    width: 100vw;
    margin: 0;
    padding: 0;
  }
  
  .three-columns {
    height: 100%;
    width: 100%;
    margin: 0;
    padding: 0;
    display: grid;
    grid-template-columns: 1fr auto 1fr;
  }
  
  .split {
    height: 100%;
    width: 100%;
  }
  
  .horizontal-gutter {
    height: 100%;
    width: 20px;
    background-color: black;
  }
  
  .terminal {
    width: 100%;
    height: 100%;
    display: grid;
    grid-template-rows: 1fr auto;
    background-color: rgb(46, 46, 46);
    font-family: "Roboto Mono", monospace;
    font-size: 16px;
    overflow: hidden;
  }
  
  .output-buffer {
    width: 100%;
    height: 100%;
    overflow-y: auto;
    overflow-x: auto;
    color: white;
  }
  
  .input-wrapper {
    width: 100%;
    display: grid;
    grid-template-columns: auto 1fr;
    background-color: rgb(69, 64, 64);
    padding: 5px;
  }
  
  .command-input {
    height: 100%;
    width: 100%;
    background-color: rgb(69, 64, 64);
    border: none;
    color: white;
    font-family: "Roboto Mono", monospace;
    font-size: 16px;
  }
</style>

<body>
  <div id="main" class="three-columns">
    <div id="split-1" class="split">
      <div class="terminal">
        <div id="output" class="output-buffer">
          <p>This is an output buffer that is expected to have scrollbars on this div when the content exceeds its size. Instead it expands. 😒</p>
          <!-- Repeated content will be generated here by JavaScript -->
        </div>
        <div id="input" class="input-wrapper">
          <input id="command-input" type="text" placeholder="> command" autocomplete="off" class="command-input" />
        </div>
      </div>
    </div>
    <div class="horizontal-gutter"></div>
    <div id="split-2" class="split">
      <div style="background-color: rgb(72, 0, 0); height: 100%; width: 100%;" />
    </div>
  </div>

  <script>
    // Get the output buffer element
    var outputBuffer = document.getElementById('output');

    // Generate many paragraphs of psuedo-content
    // to overflow the output buffer and show the problem
    for (var i = 0; i < 50; i++) {
      var p = document.createElement('p');
      p.textContent = 'All your base are belong to us!';
      outputBuffer.appendChild(p);
    }
  </script>
</body>
</html>

问题根源在于Grid布局的默认行为：网格项的min-height默认值为auto，这意味着即便你给output-buffer设置了height: 100%，当内容超出时，容器仍会自动扩展以适应内容，导致overflow-y: auto无法触发。

只需修改output-buffer的CSS，添加min-height: 0覆盖默认行为即可：

.output-buffer {
  width: 100%;
  height: 100%;
  min-height: 0; /* 关键修改项 */
  overflow-y: auto;
  overflow-x: auto;
  color: white;
}

添加后，output-buffer会严格遵循设置的高度限制，当内容垂直溢出时自动显示滚动条，同时保留原有水平滚动的正常功能。

内容的提问来源于stack exchange，提问作者David Whatley