​x
 
<!DOCTYPE html>
<html>
<head>
<style> 
div#main {
  width: 220px;
  height: 300px;
  border: 1px solid black;
  display: flex;
  align-items: center;
}
​
div#main div {
  flex: 1;
}
</style>
</head>
​
<body>
<h1>HTML Style 对象</h1>
​
<h2>alignItems 属性</h2>
​
<div id="main">
  <div style="background-color:coral;">红色</div>
  <div style="background-color:lightblue;">蓝色</div>  
  <div style="background-color:lightgreen;">有更多内容的绿色 DIV。</div>
</div>
​
<p>单击按钮将 alignItems 属性的值设置为“flex-start”。</p>
​
<button onclick="myFunction()">试一试</button>
​
<script>
function myFunction() {
  document.getElementById("main").style.alignItems = "flex-start";
}
</script>
​
</body>
</html>
​