text-size-adjust CSS property
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The text-size-adjust CSS property controls the text inflation algorithm used on some smartphones and tablets. Other browsers will ignore this property.
Because many websites have not been developed with small devices in mind, mobile browsers differ from desktop browsers in the way they render web pages. Instead of laying out pages at the width of the device screen, they lay them out using a viewport that is much wider, usually 800 or 1000 pixels. To map the extra-wide layout back to the original device size, they either show only part of the whole render or scale the viewport down to fit.
Since text that has been scaled down to fit a mobile screen may be very small, many mobile browsers apply a text inflation algorithm to enlarge the text to make it more readable. When an element containing text uses 100% of the screen's width, the algorithm increases its text size, but without modifying the layout. The text-size-adjust property allows web authors to disable or modify this behavior, as web pages designed with small screens in mind do not need it.
Syntax
/* Keyword values */
text-size-adjust: none;
text-size-adjust: auto;
/* <percentage> value */
text-size-adjust: 80%;
/* Global values */
text-size-adjust: inherit;
text-size-adjust: initial;
text-size-adjust: revert;
text-size-adjust: revert-layer;
text-size-adjust: unset;
The text-size-adjust property is specified as none, auto, or a <percentage>.
Values
none-
Disables the browser's inflation algorithm.
auto-
Enables the browser's inflation algorithm. This value is used to cancel a
nonevalue previously set with CSS. <percentage>-
Enables the browser's inflation algorithm, specifying a percentage value with which to increase the font size.
Formal definition
| Initial value | auto for smartphone browsers supporting inflation, none in other cases (and then not modifiable). |
|---|---|
| Applies to | all elements |
| Inherited | yes |
| Percentages | yes, refer to the corresponding size of the text font |
| Computed value | as specified |
| Animation type | by computed value type |
Formal syntax
text-size-adjust =
auto |
none |
<percentage [0,∞]>
Examples
Basic disabling usage
As hinted at above, on a properly designed responsive site the text-size-adjust behavior is not needed, so developers can elect to turn it off by specifying a value of none:
p {
-webkit-text-size-adjust: none;
text-size-adjust: none;
}
Specifications
| Specification |
|---|
| CSS Mobile Text Size Adjustment Module Level 1 # adjustment-control |
Browser compatibility
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text-size-adjust
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auto
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none
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<percentage>
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Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support
- No support
- No support
- Experimental. Expect behavior to change in the future.
- Requires a vendor prefix or different name for use.
- Has more compatibility info.
See also
- Apple's documentation (2016)
- Google Chrome behavior description (2014)
- Gecko's behavior description, by L. David Baron (2011)