CSS：上面固定高度、下面填充满，上面消失，下面仍然填充满

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<style>
  html, body {
  height: 100%;
  margin: 0;
}

.container {
  display: flex;
  flex-direction: column;
  height: 100%; /* 使用最小高度来确保占据整个屏幕 */
}

.top {
  height: 100px;
  background-color: lightgray;
}

.bottom {
  flex-grow: 1;
  background-color: lightblue;
}
</style>
<body>
  <div class="container">
    <div class="top">上</div>
    <div class="bottom">下</div>
  </div>
</body>
</html>