16 Text

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

16.1 Indentation: the 'text-indent' property

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.

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

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

left , right , center , andleft, right, center, justify

Left, right, center, and doublejustify text, respectively.

<string> Specifies a string on which cells in a table column will align (see the section on horizontal alignment in a column for details and an example). This value applies only to table cells. If set on other elements, it will be treated as 'left' or 'right', depending on whether 'direction' is 'ltr', or 'rtl', 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.

 DIV.centerdiv.important { text-align: center }

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

This property describes decorations that are added to the text of an element. If the property is specified for a block-level element, it affects all inline-level descendants ofelement using the element. If it iselement's color. When specified for (or affects)on an inline-levelinline element, it affects all the boxes generated by that element; for all other elements, the element. If the element has no content or no text content (e.g.,decorations are propagated to an anonymous inline box that wraps all the in-flow inline children of the element, and to any block-level in-flow descendants. It is not, however, further propagated to floating and absolutely positioned descendants, nor to the IMGcontents of 'inline-table' and 'inline-block' descendants.

If an element contains no text (ignoring white space in HTML),elements that have 'white-space' set to 'normal', 'pre-line', or 'no-wrap'), user agents must ignore this property.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 middlemiddle.

blink

Text blinks (alternates between visible and invisible). Conforming user agents aremay simply not requiredblink the text. Note that not blinking the text is one technique to support this value.satisfy checkpoint 3.3 of WAI-UAAG.

The color(s) required for the text decoration shouldmust be derived from the 'color' property value. This property is not inherited, but descendant boxesvalue of a block box should be formatted withthe same decoration (e.g., they should all be underlined).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.)

 A[href]a:visited,a:link { text-decoration: underline }

   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>

16.4 Letter and below the element's text and will be red with no blurring. The second shadow will overlay the first shadow effect, and it will be yellow, blurred, and placed to the left and below the text. The third shadow effect will be placed to the right and above the text. Since no shadow color is specified for the third shadow effect, the value of the element's 'color' property will be used: H2 { text-shadow: 3px 3px red, yellow -3px 3px 2px, 3px -3px } Example(s): Consider this example: SPAN.glow { background: white; color: white; text-shadow: black 0px 0px 5px; } Here, the 'background' and 'color' properties have the same value and the 'text-shadow' property is used to create a "solar eclipse" effect:     [D] Note. This property is not defined in CSS1. Some shadow effects (such as the one in the last example) may render text invisible in UAs that only support CSS1. 16.4 Letter and word spacing :word spacing: the 'letter-spacing' and 'word-spacing' properties

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.

blockquote { letter-spacing: 0.1em }

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.

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.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). When white space is preserved, e.g. with 'white-space:pre', all space characters are affected by word-spacing.

h1 { word-spacing: 1em }

Conforming user agents may consider the value of the 'word-spacing' property to be 'normal'.16.5 Capitalization: the 'text-transform' property

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; other characters are unaffected.

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 20703066 ( [RFC2070][RFC3066]) 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 languageswriting scripts for which the transformationthere is different from that specified by the case-conversion tables of ISO 10646 ( [ISO10646] ).no transform.

h1 { text-transform: uppercase }

16.6 Whitespace: the 'white-space' property

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.

Additional line breaks may be created by occurrences of "\A" in generated content (e.g., for the BR element in HTML).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 except for those created by "\A"text.

pre-wrap

This value prevents user agents from collapsing sequences of whitespace. Lines are broken at newlines in generated content (e.g., forthe BR elementsource, at occurrences of "\A" in HTML). Example(s): The following examples show what whitespace behavior is expected from the PREgenerated content, and P elements,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.

pre        { white-space: pre }
p          { white-space: normal }
td[nowrap] { white-space: nowrap }
 Conforming user agents may ignore:before,:after { white-space: pre-line }

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

16.6.1 The 'white-space' property in author and user style sheets but must specifyprocessing model

Any text that is directly contained inside a valueblock (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 default style sheet.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.