The font-optical-sizing
CSS property sets whether text rendering is optimized for viewing at different sizes. This only works for fonts that have an optical size variation axis.
For example, small text sizes are often rendered with thicker strokes and larger serifs, whereas larger text is often rendered more delicately with more contrast between thicker and thinner strokes.
Note: The optical size variation axis is represented by opsz
in font-variation-settings
.
Syntax
/* keyword values */ font-optical-sizing: none; font-optical-sizing: auto; /* default */ /* Global values */ font-optical-sizing: inherit; font-optical-sizing: initial; font-optical-sizing: unset;
Values
- none
- The browser will not modify the shape of glyphs for optimal viewing.
- auto
- The browser will modify the shape of glyphs for optimal viewing.
Formal syntax
auto | none
Examples
<p class="optical-sizing">This paragraph is optically sized. This is the default across browsers.</p> <p class="no-optical-sizing">This paragraph is not optically sized. You should see a difference in supporting browsers.</p>
@font-face { src: url('AmstelvarAlpha-VF.ttf'); font-family:'Amstelvar'; font-style: normal; } p { font-size: 36px; font-family: Amstelvar; } .no-optical-sizing { font-optical-sizing: none; }
Note: The font referenced above — which includes optical sizing and is freely-licensed — is good for testing. You can download it on GitHub.
Specifications
Specification | Status | Comment |
---|---|---|
CSS Fonts Module Level 4 The definition of 'font-optical-sizing' in that specification. |
Working Draft |
Initial value | auto |
---|---|
Applies to | all elements. It also applies to ::first-letter and ::first-line . |
Inherited | yes |
Media | visual |
Computed value | as specified |
Animation type | discrete |
Canonical order | per grammar |
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
font-optical-sizing | Chrome Full support 79 | Edge Full support 17 | Firefox
Full support
62
| IE No support No | Opera No support No | Safari Full support 11 | WebView Android Full support 79 | Chrome Android Full support 79 | Firefox Android
Full support
62
| Opera Android ? | Safari iOS Full support 11 | Samsung Internet Android ? |
Legend
- Full support
- Full support
- No support
- No support
- Compatibility unknown
- Compatibility unknown
- User must explicitly enable this feature.
- User must explicitly enable this feature.