PHP Editor Review - Css2reference 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.

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.

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

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

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.

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


div.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 using the element's color. When specified on an inline element, it affects all the boxes generated by that element; for all other elements, the 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 contents of 'inline-table' and 'inline-block' descendants.

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.

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.)

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 }

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 also underlined, as it is in an in-flow block to which the underline is propagated. The final line of text is fuchsia, but the underline underneath it is still the blue underline from the anonymous inline element.

Sample rendering of the above underline example

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

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

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.

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

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.

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

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

The actual transformation in each case is written language dependent. See RFC 3066 ([RFC3066]) for ways to find the language of an element.

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

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

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, treating bidi formatting characters as if they were not there:

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

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):

...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:

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:

Note that there are two spaces between A and B, and none between B and C. This can sometimes be avoided by using the natural bidirectionality of characters instead of explicit embedding levels. Also, it is good to avoid spaces immediately inside start and end tags, as these tend to do weird things when dealing with white space collapsing.

16.6.3 Control and combining characters' details

Control characters other than U+0009 (tab), U+000A (line feed), U+0020 (space), and U+202x (bidi formatting characters) are treated as characters to render in the same way as any normal character.

Combining characters should be treated as part of the character with which they are supposed to combine. For example, :first-letter styles the entire glyph if you have content like "o<span>̈</span>"; it doesn't just match the base character.

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