<!-- 把如下代码加入<body>区域中 -->
<style>
.ft{font-family:Arial; font-size:20px}
</style>
<a class=ft onClick="f();">ABCDE</a>
<script>
function f(){
document.styleSheets[0].cssText=".ft{font-family:Arial; font-size:10px}"
}
</script>
<!-- 把如下代码加入<body>区域中 -->
<style>
.ft{font-family:Arial; font-size:20px}
</style>
<a class=ft onClick="f();">ABCDE</a>
<script>
function f(){
document.styleSheets[0].cssText=".ft{font-family:Arial; font-size:10px}"
}
</script>