degrade gracefully

基本解释

HTML 5 was explicitly designed to degrade gracefully in browsers that don't support it.
HTML 5 的设计原则就是在不支持它的浏览器中能够平稳地退化。
Most of the time, you want to degrade gracefully or return a polite message to the user.
大多数情况下，您要柔和或有礼貌的消息返回给用户。
If this is done well, earlier versions of applications can even degrade relatively gracefully when they read newer saved documents -- usually by just ignoring unfamiliar tags and attributes.
如果做得好，应用程序的早期版本在读取较新的保存文档时甚至可以相对温婉地降级使用——通常只需要忽略不能识别的标签和属性。