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 value | normal |
---|---|
Applies to | all elements, though some values have no effect on non-inline elements |
Inherited | no |
Media | visual |
Computed value | as specified |
Animation type | discrete |
Canonical order | the 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 thebidi-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
.bible-quote { direction: rtl; unicode-bidi: embed; }
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).