CSS unicode-bidi Managing Bidirectional Text Effectively

Introduction

The unicode-bidi CSS property helps manage bidirectional text, which mixes left-to-right and right-to-left scripts. It’s particularly useful for multilingual websites. While user agents usually handle this with a complex Unicode algorithm, unicode-bidi gives developers control over text embedding.

Specification

The unicode-bidi property is defined in the CSS Writing Modes Level 4 specification. You can find the current specification here:

• CSS Writing Modes Level 4 # unicode-bidi

Description

The unicode-bidi property controls the embedding level of bidirectional text. It helps manage text direction in documents with mixed scripts. This property can override the normal bidirectional algorithm, which is crucial for ensuring correct text display in multilingual content.

Syntax

The syntax for the unicode-bidi property is:

/* 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

• Default value. No additional embedding level.

embed

• Adds an embedding level for inline elements. Direction is set by the direction property.

bidi-override

• Overrides the bidirectional algorithm. Text is displayed in sequence according to the direction property.

isolate

• Isolates the element from its siblings. Directionality is calculated without considering the content of this element.

isolate-override

• Combines the behaviors of isolate and bidi-override.

plaintext

• Directionality is calculated without considering the parent bidirectional state or the direction property. Useful for pre-formatted text.

Formal Definition

• Initial Value: normal
• Applies To: All elements, but some values have no effect on non-inline elements.
• Inherited: No
• Computed Value: As specified
• Animation Type: Not animatable
• Formal Syntax:

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

Examples

Here are practical examples of how to use the unicode-bidi property:

Using embed

CSS:

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

HTML:

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

Using bidi-override

CSS:

.custom-text {
  direction: rtl;
  unicode-bidi: bidi-override;
}

HTML:

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

Using isolate

CSS:

.isolated-text {
  direction: rtl;
  unicode-bidi: isolate;
}

HTML:

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

Using isolate-override

CSS:

.mixed-text {
  direction: rtl;
  unicode-bidi: isolate-override;
}

HTML:

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

Using plaintext

CSS:

.plain-text {
  unicode-bidi: plaintext;
}

HTML:

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

Browser Compatibility

The unicode-bidi CSS property is widely supported across major web browsers, making it a reliable tool for managing bidirectional text in your projects. Here’s a quick overview of browser compatibility:

• Google Chrome: Supported since version 2.0.
• Microsoft Edge: Supported since version 12.0.
• Internet Explorer: Supported since version 5.5.
• Mozilla Firefox: Supported since version 1.0.
• Safari: Supported since version 1.3.
• Opera: Supported since version 9.2.

Browser Compatibility Table

See Also

For further reading and to deepen your understanding of the unicode-bidi property, check out these resources:

• MDN Web Docs - CSS unicode-bidi WebsiteUrl: Comprehensive documentation, including explanations, examples, and compatibility information.
• CSS Writing Modes Level 4 Specification WebsiteUrl: Outlines rules and behaviors for handling bidirectional text in CSS.
• Unicode Bidirectional Algorithm WebsiteUrl: Detailed documentation on the bidirectional algorithm by the Unicode Consortium.
• Can I Use - unicode-bidi WebsiteUrl: Useful tool for checking browser compatibility.
• W3C CSS Writing Modes Module WebsiteUrl: Official specification for the CSS Writing Modes module, including the unicode-bidi property.
• CSS Tricks - unicode-bidi WebsiteUrl: Practical tips and best practices for using the unicode-bidi property.