Media types

# 7 Media types

Contents

## 7.1 Introduction to media types

One of the most important features of style sheets is that they specify how a document is to be presented on different media: on the screen, on paper, with a speech synthesizer, with a braille device, etc.

Certain CSS properties are only designed for certain media (e.g., the 'page-break-before' property only applies to paged media). On occasion, however, style sheets for different media types may share a property, but require different values for that property. For example, the 'font-size' property is useful both for screen and print media. The two media types are different enough to require different values for the common property; a document will typically need a larger font on a computer screen than on paper. Therefore, it is necessary to express that a style sheet, or a section of a style sheet, applies to certain media types.

## 7.2 Specifying media-dependent style sheets

There are currently two ways to specify media dependencies for style sheets:

- Specify the target medium from a style sheet with the @media or @import at-rules.

  Example(s):

      @import url("fancyfonts.css") screen;
      @media print {
        /* style sheet for print goes here */
      }

- Specify the target medium within the document language. For example, in HTML 4.0 ([HTML40]), the "media" attribute on the LINK element specifies the target media of an external style sheet:

      <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">
      <HTML>
         <HEAD>
            <TITLE>Link to a target medium</TITLE>
            <LINK REL="stylesheet" TYPE="text/css"
      	 MEDIA="print, handheld" HREF="foo.css">
         </HEAD>
         <BODY>
            <P>The body...
         </BODY>
      </HTML>

The @import rule is defined in the chapter on the cascade.

### 7.2.1 The @media rule

An @media rule specifies the target media types (separated by commas) of a set of rules (delimited by curly braces). The @media construct allows style sheet rules for various media in the same style sheet:

      @media print {
        body { font-size: 10pt }
      }
      @media screen {
        body { font-size: 13px }
      }
      @media screen, print {
        body { line-height: 1.2 }
      }

## 7.3 Recognized media types

The names chosen for CSS media types reflect target devices for which the relevant properties make sense. The names of media types are normative. In the following list of CSS media types, the parenthetical descriptions are not normative. Likewise, the "Media" field in the description of each property is informative.

all
  Suitable for all devices.
braille
  Intended for braille tactile feedback devices.
embossed
  Intended for paged braille printers.
handheld
  Intended for handheld devices (typically small screen, limited bandwidth).
print
  Intended for paged material and for documents viewed on screen in print preview mode. Please consult the section on paged media for information about formatting issues that are specific to paged media.
projection
  Intended for projected presentations, for example projectors. Please consult the section on paged media for information about formatting issues that are specific to paged media.
screen
  Intended primarily for color computer screens.
speech
  Intended for speech synthesizers. Note: CSS2 had a similar media type called 'aural' for this purpose. See the appendix on aural style sheets for details.
tty
  Intended for media using a fixed-pitch character grid (such as teletypes, terminals, or portable devices with limited display capabilities). Authors should not use pixel units with the "tty" media type.
tv
  Intended for television-type devices (low resolution, color, limited-scrollability screens, sound available).

Media type names are case-insensitive.

Media types are mutually exclusive in the sense that a user agent can only support one media type when rendering a document. However, user agents may have different modes which support different media types.

Note. Future versions of CSS may extend this list. Authors should not rely on media type names that are not yet defined by a CSS specification.

### 7.3.1 Media groups

This section is informative, not normative.

Each CSS property definition specifies the media types for which the property must be implemented by a conforming user agent. Since properties generally apply to several media, the "Applies to media" section of each property definition lists media groups rather than individual media types. Each property applies to all media types in the media groups listed in its definition.

CSS 2.1 defines the following media groups:

- continuous or paged.
- visual, audio, speech, or tactile.
- grid (for character grid devices), or bitmap.
- interactive (for devices that allow user interaction), or static (for those that don't).
- all (includes all media types)

The following table shows the relationships between media groups and media types:

Relationship between media groups and media types
Media Types | Media Groups
--- | ---
| continuous/paged | visual/audio/speech/tactile | grid/bitmap | interactive/static
braille | continuous | tactile | grid | both
emboss | paged | tactile | grid | static
handheld | both | visual, audio, speech | both | both
print | paged | visual | bitmap | static
projection | paged | visual | bitmap | interactive
screen | continuous | visual, audio | bitmap | both
speech | continuous | speech | N/A | both
tty | continuous | visual | grid | both
tv | both | visual, audio | bitmap | both