console 命令行工具 X clear

console

<html>
  
  <body>
    <div class="outer">
      <div class="inner">
        Hello
      </div>
    </div>
  </body>

</html>

html,
body {
  height: 100%;
  margin: 0;
}

.outer {
  background-color: lightgreen;
  height: 100%;
  box-sizing: border-box;
}

.inner {
  margin-top: 20px;
  background-color: yellow;
}