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# 16 Text

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The properties defined in the following sections affect the visual presentation of characters, spaces, words, and paragraphs.

## 16.1 Indentation: the 'text-indent' property

'text-indent'

  Value: | <length> | <percentage> | inherit
  Initial: | 0
  Applies to: | block-level elements, table cells and inline blocks
  Inherited: | yes
  Percentages: | refer to width of containing block
  Media: | visual
  Computed value: | the percentage as specified or the absolute length

This property specifies the indentation of the first line of text in a block. More precisely, it specifies the indentation of the first box that flows into the block's first line box. The box is indented with respect to the left (or right, for right-to-left layout) edge of the line box. User agents should render this indentation as blank space.

Values have the following meanings:

<length>
  The indentation is a fixed length.
<percentage>
  The indentation is a percentage of the containing block width.

The value of 'text-indent' may be negative, but there may be implementation-specific limits. If the value of 'text-indent' is either negative or exceeds the width of the block, that first box, described above, may overflow the block. The value of 'overflow' will affect whether such text that overflows the block is visible.

Example(s):

The following example causes a '3em' text indent.

    p { text-indent: 3em }

Note: Since the 'text-indent' property inherits, when specified on a block element, it will affect descendent inline-block elements. For this reason, it is often wise to specify '`text-indent: 0`' on elements that are specified '`display:inline-block`'.

## 16.2 Alignment: the 'text-align' property

'text-align'

  Value: | left | right | center | justify | inherit
  Initial: | 'left' if 'direction' is 'ltr'; 'right' if 'direction' is 'rtl'
  Applies to: | block-level elements and table cells
  Inherited: | yes
  Percentages: | N/A
  Media: | visual
  Computed value: | as specified

This property describes how inline content of a block is aligned. Values have the following meanings:

left, right, center, justify
  Left, right, center, and justify text, respectively.

A block of text is a stack of line boxes. In the case of 'left', 'right' and 'center', this property specifies how the inline boxes within each line box align with respect to the line box's left and right sides; alignment is not with respect to the viewport. In the case of 'justify', the UA may stretch the inline boxes in addition to adjusting their positions. (See also 'letter-spacing' and 'word-spacing'.)

If the computed value of text-align is 'justify' while the computed value of white-space is 'pre' or 'pre-line', the actual value of text-align is set to the initial value.

Example(s):

In this example, note that since 'text-align' is inherited, all block-level elements inside the DIV element with 'class=important' will have their inline content centered.

    div.important { text-align: center }

Note. The actual justification algorithm used depends on the user-agent and the language/script of the text.

Conforming user agents may interpret the value 'justify' as 'left' or 'right', depending on whether the element's default writing direction is left-to-right or right-to-left, respectively.

## 16.3 Decoration

### 16.3.1 Underlining, overlining, striking, and blinking: the 'text-decoration' property

'text-decoration'

  Value: | none | [ underline || overline || line-through || blink ] | inherit
  Initial: | none
  Applies to: | all elements
  Inherited: | no (see prose)
  Percentages: | N/A
  Media: | visual
  Computed value: | as specified

This property describes decorations that are added to the text of an element. When specified on an inline element, it affects all the boxes generated by that element, otherwise, the decorations are propagated to the anonymous inline box that wraps all the inline contents of the element, using the element's color. It is not, however, further propagated to floating and absolutely positioned descendants, nor to the contents of 'inline-table' and 'inline-block' descendants. Nor is it propagated to block-level descendants of inline elements.

If an element contains no text (ignoring white space in elements that have 'white-space' set to 'normal', 'pre-line', or 'no-wrap'), user agents must refrain from rendering text decorations on the element. For example, elements containing only images and collapsed white space will not be underlined.

Text decorations on inline boxes are drawn across the entire element, going across any descendant elements without paying any attention to their presence. The 'text-decoration' property on descendant elements cannot have any effect on the decoration of the element. In determining the position of and thickness of text decoration lines, user agents may consider the font sizes of and dominant baselines of descendants, but must use the same baseline and thickness on each line.

Values have the following meanings:

none
  Produces no text decoration.
underline
  Each line of text is underlined.
overline
  Each line of text has a line above it.
line-through
  Each line of text has a line through the middle.
blink
  Text blinks (alternates between visible and invisible). Conforming user agents may simply not blink the text. Note that not blinking the text is one technique to satisfy checkpoint 3.3 of WAI-UAAG.

The color(s) required for the text decoration must be derived from the 'color' property value of the element on which 'text-decoration' is set. The color of decorations should remain the same even if descendant elements have different 'color' values.

Some user agents have implemented text-decoration by propagating the decoration to the descendant elements as opposed to simply drawing the decoration through the elements as described above. This was arguably allowed by the looser wording in CSS2. SVG1, CSS1-only, and CSS2-only user agents may implement the older model and still claim conformance to this part of CSS2.1. (This does not apply to UAs developed after this specification was released.)

Example(s):

In the following example for HTML, the text content of all A elements acting as hyperlinks (whether visited or not) will be underlined:

    a:visited,a:link { text-decoration: underline }

Example(s):

In the following stylesheet and document fragment:

       blockquote { text-decoration: underline; color: blue; }
       em { display: block; }
       cite { color: fuchsia; }

       <blockquote>
        <p>
         <span>
          Help, help!
          <em> I am under a hat! </em>
          <cite> —GwieF </cite>
         </span>
        </p>
       </blockquote>

...the underlining for the blockquote element is propagated to an anonymous inline element that surrounds the span element, causing the text "Help, help!" to be blue, with the blue underlining from the anonymous inline underneath it, the color being taken from the blockquote element. The `<em>text</em>` in the em block is not underlined at all, as it is not contained in the same anonymous inline element. The final line of text is fuchsia, but the underline underneath it is still the blue underline from the anonymous inline element.

This diagram shows the boxes involved in the example above. The rounded aqua line represents the anonymous inline element wrapping the inline contents of the paragraph element, the rounded blue line represents the span element, and the orange lines represent the blocks.

## 16.4 Letter and word spacing: the 'letter-spacing' and 'word-spacing' properties

'letter-spacing'

  Value: | normal | <length> | inherit
  Initial: | normal
  Applies to: | all elements
  Inherited: | yes
  Percentages: | N/A
  Media: | visual
  Computed value: | 'normal' or absolute length

This property specifies spacing behavior between text characters. Values have the following meanings:

normal
  The spacing is the normal spacing for the current font. This value allows the user agent to alter the space between characters in order to justify text.
<length>
  This value indicates inter-character space in addition to the default space between characters. Values may be negative, but there may be implementation-specific limits. User agents may not further increase or decrease the inter-character space in order to justify text.

Character spacing algorithms are user agent-dependent.

Example(s):

In this example, the space between characters in BLOCKQUOTE elements is increased by '0.1em'.

    blockquote { letter-spacing: 0.1em }

In the following example, the user agent is not permitted to alter inter-character space:

    blockquote { letter-spacing: 0cm }   /* Same as '0' */

When the resultant space between two characters is not the same as the default space, user agents should not use ligatures.

'word-spacing'

  Value: | normal | <length> | inherit
  Initial: | normal
  Applies to: | all elements
  Inherited: | yes
  Percentages: | N/A
  Media: | visual
  Computed value: | for 'normal' the value '0'; otherwise the absolute length

This property specifies spacing behavior between words. Values have the following meanings:

normal
  The normal inter-word space, as defined by the current font and/or the UA.
<length>
  This value indicates inter-word space in addition to the default space between words. Values may be negative, but there may be implementation-specific limits.

Word spacing algorithms are user agent-dependent. Word spacing is also influenced by justification (see the 'text-align' property).

Example(s):

In this example, the word-spacing between each word in H1 elements is increased by '1em'.

    h1 { word-spacing: 1em }

## 16.5 Capitalization: the 'text-transform' property

'text-transform'

  Value: | capitalize | uppercase | lowercase | none | inherit
  Initial: | none
  Applies to: | all elements
  Inherited: | yes
  Percentages: | N/A
  Media: | visual
  Computed value: | as specified

This property controls capitalization effects of an element's text. Values have the following meanings:

capitalize
  Puts the first character of each word in uppercase.
uppercase
  Puts all characters of each word in uppercase.
lowercase
  Puts all characters of each word in lowercase.
none
  No capitalization effects.

The actual transformation in each case is written language dependent. See RFC 2070 ([RFC2070]) for ways to find the language of an element.

Conforming user agents may consider the value of 'text-transform' to be 'none' for characters that are not from the Latin-1 repertoire and for elements in languages for which the transformation is different from that specified by the case-conversion tables of ISO 10646 ([ISO10646]).

Example(s):

In this example, all text in an H1 element is transformed to uppercase text.

    h1 { text-transform: uppercase }

## 16.6 Whitespace: the 'white-space' property

'white-space'

  Value: | normal | pre | nowrap | pre-wrap | pre-line | inherit
  Initial: | normal
  Applies to: | all elements
  Inherited: | yes
  Percentages: | N/A
  Media: | visual
  Computed value: | as specified

This property declares how whitespace inside the element is handled. Values have the following meanings:

normal
  This value directs user agents to collapse sequences of whitespace, and break lines as necessary to fill line boxes.
pre
  This value prevents user agents from collapsing sequences of whitespace. Lines are only broken at newlines in the source, or at occurrences of "\A" in generated content.
nowrap
  This value collapses whitespace as for 'normal', but suppresses line breaks within text.
pre-wrap
  This value prevents user agents from collapsing sequences of whitespace. Lines are broken at newlines in the source, at occurrences of "\A" in generated content, and as necessary to fill line boxes.
pre-line
  This value directs user agents to collapse sequences of whitespace. Lines are broken at newlines in the source, at occurrences of "\A" in generated content, and as necessary to fill line boxes.

Example(s):

The following examples show what whitespace behavior is expected from the PRE and P elements, the "nowrap" attribute in HTML, and in generated content.

    pre        { white-space: pre }
    p          { white-space: normal }
    td[nowrap] { white-space: nowrap }
    :before,:after { white-space: pre-line }

In addition, the effect of an HTML PRE element with the non-standard "wrap" attribute is demonstrated by the following example:

    pre[wrap]  { white-space: pre-wrap }

### 16.6.1 The 'white-space' processing model

Any text that is directly contained inside a block (not inside an inline) should be treated as an anonymous inline element.

For each inline (including anonymous inlines), the following steps are performed, ignoring bidi formatting characters as if they were not there:

1. Each non-linefeed whitespace character surrounding a linefeed character is removed if 'white-space' is set to 'normal', 'no-wrap', or 'pre-line'.
2. If 'white-space' is set to 'pre' or 'pre-wrap', any sequence of spaces (U+0020) unbroken by an element boundary is treated as a sequence of non-breaking spaces. However, a line breaking opportunity exists at the end of the sequence.
3. If 'white-space' is set to 'normal' or 'nowrap', linefeed characters are transformed for rendering purpose into one of the following characters: a space character, a zero width space character (U+200B), or no character (i.e. not rendered), according to UA-specific algorithms based on the content script.
4. If 'white-space' is set to 'normal', 'nowrap', or 'pre-line',
   1. every tab (U+0009) is converted to a space (U+0020)
   2. any space (U+0020) following another space (U+0020) — even a space before the inline, if that space also has 'white-space' set to 'normal', 'nowrap' or 'pre-line' — is removed.

Then, the entire block is rendered. Inlines are laid out, taking bidi reordering into account, and wrapping as specified by the 'white-space' property.

As each line is laid out,

1. If a space (U+0020) at the beginning of a line has 'white-space' set to 'normal', 'nowrap', or 'pre-line', it is removed.
2. All tabs (U+0009) are rendered as a horizontal shift that lines up the start edge of the next glyph with the next tab stop. Tab stops occur at points that are mutiples of 8 times the width of a space (U+0020) rendered in the block's font from the block's starting content edge.
3. If a space (U+0020) at the end of a line has 'white-space' set to 'normal', 'nowrap', or 'pre-line', it is also removed.

### 16.6.2 Example of bidirectionality with white-space collapsing

Given the following markup fragment, taking special note of spaces (with varied backgrounds and borders for emphasis and identification):

         <ltr>A <rtl> B </rtl> C</ltr>

...where the `<ltr>` element represents a left-to-right embedding and the `<rtl>` element represents a right-to-left embedding, and assuming that the 'white-space' property is set to 'normal', the above processing model would result in the following:

- The space before the B ( ) would collapse with the space after the A ( ).
- The space before the C ( ) would collapse with the space after the B ( ).

This would leave two spaces, one after the A in the left-to-right embedding level, and one after the B in the right-to-left embedding level. This is then rendered according to the Unicode bidirectional algorithm, with the end result being:

         A  BC

Note that there are two spaces between A and B, and none between B and C. This is best avoided by using the natural bidirectionality of characters instead of explicit embedding levels.