<!DOCTYPE html>
<html>
<title>W3.CSS</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://www.w3schools.cn/w3css/4/w3.css">
<body>
<div class="w3-container">
<h2>移动优先响应</h2>
<p class="w3-large">尝试调整窗口大小！</p>
</div>
<div class="w3-row w3-border">
<div class="w3-third w3-container w3-red">
<h2>w3-third</h2>
<p>w3-third 类使用父容器的 33%。</p>
<p>在小于 601 像素的屏幕上，它会调整为全屏。</p>
</div>
<div class="w3-third w3-container">
<h2>w3-third</h2>
</div>
<div class="w3-third w3-container">
<h2>w3-third</h2>
</div>
</div>
</body>
</html>