​x
 
<!DOCTYPE html>
<html>
<head>
<style> 
#myDIV {
  border: 1px solid black;
  width: 300px;
  height: 322px;
  background: url('/i/pic/tree.png') no-repeat;
}
</style>
</head>
​
<body>
​
<p>点击“试一试”按钮可放大 DIV 元素的 background-size：</p>
​
<button onclick="myFunction()">试一试</button>
​
<div id="myDIV">
  <h1>Hello</h1>
</div>
​
<script>
function myFunction() {
  document.getElementById("myDIV").style.backgroundSize = "150px 161px";
}
</script>
​
</body>
</html>
​