font-display CSS at-rule descriptor
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.
The font-display descriptor for the @font-face at-rule determines how a font face is displayed based on whether and when it is downloaded and ready to use.
Syntax
/* Keyword values */
font-display: auto;
font-display: block;
font-display: swap;
font-display: fallback;
font-display: optional;
Values
auto-
The font display strategy is defined by the user agent.
block-
Gives the font face a short block period and an infinite swap period.
swap-
Gives the font face an extremely small block period and an infinite swap period.
fallback-
Gives the font face an extremely small block period and a short swap period.
optional-
Gives the font face an extremely small block period and no swap period.
Note:
In Firefox, the preferences gfx.downloadable_fonts.fallback_delay
and gfx.downloadable_fonts.fallback_delay_short provide the duration
of the "short" and "extremely small" periods, respectively.
Description
The font display timeline is based on a timer that begins the moment the user agent attempts to use a given downloaded font face. The timeline is divided into the three periods below which dictate the rendering behavior of any elements using the font face:
- Font block period: If the font face is not loaded, any element attempting to use it must render an invisible fallback font face. If the font face successfully loads during this period, it is used normally.
- Font swap period: If the font face is not loaded, any element attempting to use it must render a fallback font face. If the font face successfully loads during this period, it is used normally.
- Font failure period: If the font face is not loaded, the user agent treats it as a failed load causing normal font fallback.
Formal definition
| Related at-rule | @font-face |
|---|---|
| Initial value | auto |
| Computed value | as specified |
Formal syntax
font-display =
auto |
block |
swap |
fallback |
optional
Examples
Specifying fallback font-display
@font-face {
font-family: "ExampleFont";
src:
url("/path/to/fonts/example-font.woff") format("woff"),
url("/path/to/fonts/example-font.eot") format("embedded-opentype");
font-weight: normal;
font-style: normal;
font-display: fallback;
}
Specifications
| Specification |
|---|
| CSS Fonts Module Level 4 # font-display-desc |
Browser compatibility
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Legend
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- Full support
- Full support