font-synthesis

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

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

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.

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

This keyword indicates that neither bold nor italic typeface may be synthesized.

weight

This keyword indicates that a bold typeface may be synthesized if needed.

style

This keyword indicates that an italic typeface may be synthesized if needed.

Formal syntax

none | [ weight || style ]

Examples

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

Browser Compatibility