howto 在线编辑器 | howto代码测试

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>* {box-sizing: border-box}

/* 将 body 和文档的高度设置为 100% */
body, html {
  height: 100%;
  margin: 0;
  font-family: Arial;
}

/* 样式选项卡链接 */
.tablink {
  background-color: #555;
  color: white;
  float: left;
  border: none;
  outline: none;
  cursor: pointer;
  padding: 14px 16px;
  font-size: 17px;
  width: 25%;
}

.tablink:hover {
  background-color: #777;
}

/* 设置选项卡内容的样式（并为整页内容添加高度：100%）*/
.tabcontent {
  color: white;
  display: none;
  padding: 100px 20px;
  height: 100%;
}

#Home {background-color: red;}
#News {background-color: green;}
#Contact {background-color: blue;}
#About {background-color: orange;}
</style>
</head>
<body>

<button class="tablink" onclick="openPage('Home', this, 'red')">首页</button>
<button class="tablink" onclick="openPage('News', this, 'green')" id="defaultOpen">News</button>
<button class="tablink" onclick="openPage('Contact', this, 'blue')">联系方式</button>
<button class="tablink" onclick="openPage('About', this, 'orange')">About</button>

<div id="Home" class="tabcontent">
  <h3>首页</h3>
  <p>家是心之所在..</p>
</div>

<div id="News" class="tabcontent">
  <h3>News</h3>
  <p>在这个美好的日子里有消息！</p> 
</div>

<div id="Contact" class="tabcontent">
  <h3>联系方式</h3>
  <p>取得联系，或顺便喝杯咖啡。</p>
</div>

<div id="About" class="tabcontent">
  <h3>About</h3>
  <p>我们是谁，我们做什么。</p>
</div>

// 获取 id="defaultOpen" 的元素并点击它
document.getElementById("defaultOpen").click();
</script>
   
</body>
</html>

报个问题: