試一試 - CSS Reference js

<!DOCTYPE html>
<html>
<head>
<style> 
div#main {
    width: 220px;
    height: 300px;
    border: 1px solid black;
    display: -webkit-flex; /* Safari */
    -webkit-align-items: center; /* Safari 7.0+ */
    display: flex;
    align-items: center;
}

div#main div {
    -webkit-flex: 1; /* Safari 7.0+ */
    flex: 1;
}
</style>
</head>
<body>

<div id="main">
  <div style="background-color:coral;">RED</div>
  <div style="background-color:lightblue;">BLUE</div>  
  <div style="background-color:lightgreen;">Green div with more content.</div>
</div>

<p>Click the "Try it" button to set the value of the alignItems property to "flex-start"</p>
<button onclick="myFunction()">Try it</button>

<p><b>Note:</b> Internet Explorer 10 and earlier versions do not support the alignItems property.</p>

<p><b>Note:</b> Safari 7.0 (and newer) supports an alternative, the WebkitAlignItems property.</p>

</body>
</html>