page-break-before
描述 (Description)
page-break-before属性指示在元素框之前是否允许（以及多少）分页符。
此属性的值不是确定分页符是否应遵循该元素的唯一因素。 此决定还将受到前一个元素的page-break-after值以及任何祖先元素的page-break-inside值的影响。
可能的值 (Possible Values)
auto - 在元素框之前既不强制也不阻止分页符。
always - 应该在此元素的框之前强制分页。
avoid - 如果可能的话，不应在元素框之前放置分页符。
left - 在元素框之前强制执行一个或两个分页符，以便打印元素的下一页将是左侧页面。
right - 在元素框之前强制执行一个或两个分页符，以便打印元素的下一页将是右侧页面。
适用于 (Applies to)
所有块级元素。
例子 (Example)
这是一个例子 -
<html>
<head>
<style type = "text/css">
p{page-break-before: always;}
</style>
</head>
<body>
<p>
Android is an open source and Linux-based Operating System for mobile devices such as smartphones and tablet computers. Android was developed by the Open Handset Alliance, led by Google, and other companies.
Android offers a unified approach to application development for mobile devices which means developers need only develop for Android, and their applications should be able to run on different devices powered by Android.
The first beta version of the Android Software Development Kit (SDK) was released by Google in 2007 where as the first commercial version, Android 1.0, was released in September 2008.
On June 27, 2012, at the Google I/O conference, Google announced the next Android version, 4.1 Jelly Bean. Jelly Bean is an incremental update, with the primary aim of improving the user interface, both in terms of functionality and performance.
The source code for Android is available under free and open source software licenses. Google publishes most of the code under the Apache License version 2.0 and the rest, Linux kernel changes, under the GNU General Public License version 2
</p>
<p>
Android applications are usually developed in the Java language using the Android Software Development Kit.
Once developed, Android applications can be packaged easily and sold out either through a store such as Google Play or the Amazon Appstore.
Android powers hundreds of millions of mobile devices in more than 190 countries around the world. It's the largest installed base of any mobile platform and growing fast. Every day more than 1 million new Android devices are activated worldwide.
This tutorial has been written with an aim to teach you how to develop and package Android application. We will start from environment setup for Android application programming and then drill down to look into various aspects of Android applications
</p>
<button onclick = "myFunction()">Print this page</button>
<script>
function myFunction() {
window.print();
}
</script>
</body>
</html>
它会产生以下结果 -
新页面打开有关更多详细信息，请查看CSS分页媒体 。
