The font-size-adjust
CSS property sets how the font size should be chosen based on the height of lowercase rather than capital letters.
/* Use the specified font size */ font-size-adjust: none; /* Use a font size that makes lowercase letters half the specified font size */ font-size-adjust: 0.5; /* Global values */ font-size-adjust: inherit; font-size-adjust: initial; font-size-adjust: unset;
The property is useful since the legibility of fonts, especially at small sizes, is determined more by the size of lowercase letters than by the size of capital letters. Legibility can become an issue when the first-choice font-family
is unavailable and its replacement has a significantly different aspect ratio (the ratio of the size of lowercase letters to the size of the font).
To use this property in a way that is compatible with browsers that do not support font-size-adjust
, it is specified as a number that the font-size
property is multiplied by. This means the value specified for the property should generally be the aspect ratio of the first choice font. For example, a style sheet that specifies:
font-size: 14px; font-size-adjust: 0.5;
... is really specifying that the lowercase letters of the font should be 7px
high (0.5 × 14px).
Initial value | none |
---|---|
Applies to | all elements. It also applies to ::first-letter and ::first-line . |
Inherited | yes |
Media | visual |
Computed value | as specified |
Animation type | a number |
Canonical order | the unique non-ambiguous order defined by the formal grammar |
none
font-size
property.<number>
Choose the size of the font so that its lowercase letters (as determined by the x-height of the font) are the specified number times the font-size
.
The number specified should generally be the aspect ratio (ratio of x-height to font size) of the first choice font-family
. This means that the first-choice font, when available, will appear the same size in browsers, whether or not they support font-size-adjust
.
0
yields text of zero height (hidden text).
none | <number>
<p class="times">This text uses the Times font (10px), which is hard to read in small sizes.</p> <p class="verdana">This text uses the Verdana font (10px), which has relatively large lowercase letters.</p> <p class="adjtimes">This is the 10px Times, but now adjusted to the same aspect ratio as the Verdana.</p>
.times { font-family: Times, serif; font-size: 10px; } .verdana { font-family: Verdana, sans-serif; font-size: 10px; } .adjtimes { font-family: Times, sans-serif; font-size-adjust: 0.58; font-size: 10px; }
Specification | Status | Comment |
---|---|---|
CSS Fonts Module Level 3 The definition of 'font-size-adjust' in that specification. | Candidate Recommendation | Initial definition |
The CSS property font-size-adjust
was initially defined in CSS 2, but dropped in CSS 2.1. It has been newly defined in CSS 3.
Desktop | ||||||
---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | |
Basic support | 43
|
No | 40
|
No | 30
|
No |
Mobile | |||||||
---|---|---|---|---|---|---|---|
Android webview | Chrome for Android | Edge Mobile | Firefox for Android | Opera for Android | iOS Safari | Samsung Internet | |
Basic support | ? | ? | No | 4 | ? | ? | ? |
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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/CSS/font-size-adjust