css properties unicode-bidi

The unicode-bidi CSS property, together with the direction property, determines how bidirectional text in a document is handled. For example, if a block of content contains both left-to-right and right-to-left text, the user-agent uses a complex Unicode algorithm to decide how to display the text. The unicode-bidi property overrides this algorithm and allows the developer to control the text embedding.

The unicode-bidi and direction properties are the only properties that are not affected by the all shorthand.

Syntax

/* Keyword values */
unicode-bidi: normal;
unicode-bidi: embed;
unicode-bidi: isolate;
unicode-bidi: bidi-override;
unicode-bidi: isolate-override;
unicode-bidi: plaintext;

/* Global values */
unicode-bidi: inherit;
unicode-bidi: initial;
unicode-bidi: revert;
unicode-bidi: revert-layer;
unicode-bidi: unset;

Values

normal

The element does not offer an additional level of embedding with respect to the bidirectional algorithm. For inline elements, implicit reordering works across element boundaries.

embed

If the element is inline, this value opens an additional level of embedding with respect to the bidirectional algorithm. The direction of this embedding level is given by the direction property.

bidi-override

For inline elements this creates an override. For block container elements this creates an override for inline-level descendants not within another block container element. This means that inside the element, reordering is strictly in sequence according to the direction property; the implicit part of the bidirectional algorithm is ignored.

isolate

This keyword indicates that the element's container directionality should be calculated without considering the content of this element. The element is therefore isolated from its siblings. When applying its bidirectional-resolution algorithm, its container element treats it as one or several U+FFFC Object Replacement Character, i.e. like an image.

isolate-override

This keyword applies the isolation behavior of the isolate keyword to the surrounding content and the override behavior of the bidi-override keyword to the inner content.

plaintext

This keyword makes the elements directionality calculated without considering its parent bidirectional state or the value of the direction property. The directionality is calculated using the P2 and P3 rules of the Unicode Bidirectional Algorithm. This value allows the display of data that is already formatted using a tool following the Unicode Bidirectional Algorithm.

Formal definition

Formal syntax

normal | embed | isolate | bidi-override | isolate-override | plaintext

Examples

CSS

.bible-quote {
  direction: rtl;
  unicode-bidi: embed;
}

HTML

<div class="bible-quote">A line of text</div>
<div>Another line of text</div>

See also

• direction