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font-synthesis

The font-synthesis CSS property controls which missing typefaces, bold or italic, may be synthesized by the browser.

Syntax

This property can take any one of the following forms:

  • The keyword value none.
  • Either of the keyword values weight and style.
  • Both the keyword values weight and style.

Values

none
Indicates that neither bold nor italic typeface may be synthesized.
weight
Indicates that a bold typeface may be synthesized if needed.
style
Indicates that an italic typeface may be synthesized if needed.

Description

Most standard Western fonts include italic and bold variants, but many novelty fonts do not. Fonts used for Chinese, Japanese, Korean and other logographic scripts tend not to include these variants, and synthesizing them may impede the legibility of the text. In these cases, it may be desirable to switch off the browser's default font-synthesis.

Formal definition

Initial value weight style
Applies to all elements. It also applies to ::first-letter and ::first-line.
Inherited yes
Computed value as specified
Animation type discrete

Formal syntax

none | [ weight || style ]

Examples

Disabling font synthesis

HTML

<em class="syn">Synthesize me! 站直。</em>
<br/>
<em class="no-syn">Don't synthesize me! 站直。</em>

CSS

em {
  font-weight: bold;
}
.syn {
  font-synthesis: style weight;
}
.no-syn {
  font-synthesis: none;
}

Result

Specifications

Specification Status Comment
CSS Fonts Module Level 3
The definition of 'font-synthesis' in that specification.
Candidate Recommendation Initial definition

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
font-synthesis No No 34
34
33 — 34
Disabled
Disabled From version 33 until version 34 (exclusive): this feature is behind the layout.css.font-features.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
No No 9
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
font-synthesis No No 34 No 9 No

See also

© 2005–2020 Mozilla and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/CSS/font-synthesis