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.

Note: This property is intended for Document Type Definition (DTD) designers. Web designers and similar authors should not override it.

/* 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: unset;

Initial valuenormal
Applies toall elements, though some values have no effect on non-inline elements
Inheritedno
Mediavisual
Computed valueas specified
Animation typediscrete
Canonical orderthe unique non-ambiguous order defined by the formal grammar

Syntax

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 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>

Result

Specification

Specification Status Comment
CSS Writing Modes Module Level 3
The definition of 'unicode-bidi' in that specification.
Candidate Recommendation Added plaintext, isolate, and isolate-override keywords.
CSS Level 2 (Revision 1)
The definition of 'unicode-bidi' in that specification.
Recommendation Initial definition.

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 2.0 (Yes) 1.0 (1.7 or earlier) 5.5 9.2 1.3
isolate 16 -webkit[1][4]
48.0
No support 10 (10) -moz[2]
50 (50)[6]
No support No support -webkit[4]
plaintext 48.0 No support 10 (10) -moz
50 (50)[5]
No support No support No support
isolate-override 48.0 No support 17 (17) -moz
50 (50)[6]
No support No support No support
Feature Android Android Webview Edge Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile Chrome for Android
Basic support 1.0 (Yes) (Yes) 1.0 (1.0) 6 8 3.1 (Yes)
isolate ? 48.0 No support 10.0 (10) -moz
50.0 (50)[6]
No support No support No support 48.0
plaintext No support 48.0 No support 10.0 (10) -moz[3]
50.0 (50)[5]
No support No support No support 48.0
isolate-override No support 48.0 No support 17.0 (17) -moz
50.0 (50)[6]
No support No support No support 48.0

[1] Since Chrome 19, the syntax from a previous version of the spec, where the isolate keyword could be used together with bidi-override, is allowed.

[2] From Firefox 10 to Firefox 16 included, the old version of the spec, where the isolate keyword could be used together with bidi-override, was implemented. From Firefox 17, this is no longer possible: only one value is allowed and the previous isolate bidi-override can be described using the new isolate-override keyword.

[3] Up to Firefox 15, plaintext didn't do anything to an inline element. The specification changed and the implementation was fixed in Firefox 15.

[4] -webkit-isolate can lock up older versions of Safari (up to 9) and Chrome (up to 47) and is best avoided in favor of the unprefixed version.

[5] Before Firefox 50, the plaintext value was ignored for vertical writing modes (bug 1302734). The -moz prefixed version of this property was removed in Gecko 54 (Firefox 54 / Thunderbird 54 / SeaMonkey 2.51).

[6] The -moz prefixed version of this property was removed in Gecko 54 (Firefox 54 / Thunderbird 54 / SeaMonkey 2.51).

See also

Document Tags and Contributors

 Last updated by: DiD92,