font-synthesis

Baseline Widely available *

This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2022.

* Some parts of this feature may have varying levels of support.

font-synthesis CSS 属性控制浏览器可以合成（synthesize）哪些缺失的字体，粗体或斜体。

尝试一下

font-synthesis: weight style small-caps;

font-synthesis: none;

font-synthesis: weight;

font-synthesis: style;

font-synthesis: small-caps;

font-synthesis: position;

<section class="default-example" id="default-example">
  <div class="transition-all" id="example-element">
    <p class="english">
      This font does not include <span class="bold">bold</span>,
      <span class="italic">italic</span>,
      <span class="small-caps">small-caps</span>, and
      <span class="sub">subscript</span> or
      <span class="sup">superscript</span> variants.
    </p>
    <p class="chinese">
      中文排版通常不运用<span class="bold">粗体</span>或<span class="italic"
        >斜体</span
      ><span class="sub">常不</span><span class="sup">运用</span>。
    </p>
  </div>
</section>

@font-face {
  font-family: Oxygen;
  font-style: normal;
  font-weight: 400;
  src: url("https://fonts.gstatic.com/s/oxygen/v14/2sDfZG1Wl4LcnbuKjk0m.woff2")
    format("woff2");
}

/* [108] */
@font-face {
  font-family: "Ma Shan Zheng";
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url("https://fonts.gstatic.com/s/mashanzheng/v10/NaPecZTRCLxvwo41b4gvzkXaRMGEFoZJFdX0wQ5Xo5Hr21L9zCcRFhbSe5Nk0pIMuUkHEA.108.woff2")
    format("woff2");
}
/* [110] */
@font-face {
  font-family: "Ma Shan Zheng";
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url("https://fonts.gstatic.com/s/mashanzheng/v10/NaPecZTRCLxvwo41b4gvzkXaRMGEFoZJFdX0wQ5Xo5Hr21L9zCcRFhbSe5Nk0pIMuUkHEA.110.woff2")
    format("woff2");
}
/* [117] */
@font-face {
  font-family: "Ma Shan Zheng";
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url("https://fonts.gstatic.com/s/mashanzheng/v10/NaPecZTRCLxvwo41b4gvzkXaRMGEFoZJFdX0wQ5Xo5Hr21L9zCcRFhbSe5Nk0pIMuUkHEA.117.woff2")
    format("woff2");
}
/* [118] */
@font-face {
  font-family: "Ma Shan Zheng";
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url("https://fonts.gstatic.com/s/mashanzheng/v10/NaPecZTRCLxvwo41b4gvzkXaRMGEFoZJFdX0wQ5Xo5Hr21L9zCcRFhbSe5Nk0pIMuUkHEA.118.woff2")
    format("woff2");
}
/* [119] */
@font-face {
  font-family: "Ma Shan Zheng";
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url("https://fonts.gstatic.com/s/mashanzheng/v10/NaPecZTRCLxvwo41b4gvzkXaRMGEFoZJFdX0wQ5Xo5Hr21L9zCcRFhbSe5Nk0pIMuUkHEA.119.woff2")
    format("woff2");
}

.english {
  font-size: 1.2em;
  font-family: Oxygen;
}

.chinese {
  font-size: 1.2em;
  font-family: "Ma Shan Zheng";
}

.bold {
  font-weight: bold;
}

.italic {
  font-style: italic;
}

.small-caps {
  font-variant: small-caps;
}

.sub {
  font-variant: sub;
}

.sup {
  font-variant: super;
}

大多数标准西方字体包含斜体和粗体变体，但许多新颖（novelty）的字体不包括这些。用于中文、日文、韩文和其他语标文字（logographic script）的字体往往不含这些变体，同时，从默认字体中生成、合成这些变体可能会妨碍文本的易读性。在这些情况下，可能最好关闭浏览器默认的 font-synthesis 字体合成特性。

初始值weight style small-caps position
适用元素所有元素和文本. It also applies to ::first-letter and ::first-line.
是否是继承属性是
计算值as specified
动画类型离散值

语法

此属性（的值）可采用下列任意一种形式：

  • 关键词 none
  • 关键词 weight 或 style
  • 关键词 weight 和 style。

属性值

none

此关键词表示不合成粗体字型（typeface）或斜体字型。

weight

此关键词表示，如果需要的话，可以合成粗体字型。

style

此关键词表示，如果需要的话，可以合成斜体字型。

形式化语法

font-synthesis = 
  none                                           |
  [ weight || style || small-caps || position ]

示例

HTML

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

CSS

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

结果

规范

Specification
CSS Fonts Module Level 4
# font-synthesis

浏览器兼容性