html - 为什么 'projection' 是链接标记中媒体属性的无效值？

Question

根据w3.org validator :

<link rel="stylesheet" href="css/style.css" media="screen, projection, tv" />   

由于 projection 值似乎不再有效。

我记不太清了，但这样就包含了全屏 Opera。可能 Opera 也会加载带有 media="screen"的文件。

为什么现在这个无效了？是否有另一种方法可以为“全屏/投影”设备提供额外的 CSS？

Answer 1

这里是 W3C HTML 检查器的维护者。大约 3 周前，我实现并向生产 W3C HTML 检查器推送了发出这些新错误的更改；这个变化: https://github.com/validator/validator/commit/66c739a49afd050226a91f2b7f49662e0dcc9a09

我进行了更改，以便使 HTML 检查器符合当前的 CSS 媒体查询规范。如 an earlier answer 中所述:

[...] MQ4 basically deprecates all the CSS2.1 media types except all, print, screen and speech, citing the use of media feature detection instead, saying:

In addition, the following deprecated media types are defined. Authors must not use these media types; instead, it is recommended that they select appropriate media features that better represent the aspect of the device that they are attempting to style against.

据推测，验证器将值标记为无效，因为它违反了“作者不得使用这些媒体类型”的规定。