Media Queries allow authors to adapt the style applied to a document based on the environment the document is being rendered in. [HTML401] and [CSS21] introduced this mechanism, by allowing detection of the media type. For example, a document may use sans-serif fonts when displayed on a screen and serif fonts when printed. ‘screen’ and ‘print’ are two media types that have been defined. Media Queries Level 3 [MEDIAQ] refined this mechanism by allowing detection of individual characteristics, or media features. For example, a document may use a different style when displayed in ‘portrait’ and in ‘landscape’ mode, as detected by the ‘orientation’ media feature.