Each font to make it unique, there is the
value. In printing, this is a term that refers to the distance in a printed character between the baseline and the median line. In general, it corresponds to the height of the letter x of the font (it is from this that the term comes) because the other letters generally present optical corrections that increase their sizes.
property allows you to specify an optimal aspect ratio for when a fallback font is used; if the substitute font has a different aspect ratio than the preferred one, the text’s x-height will be preserved. By knowing the aspect ratio of the primary font, the browser figures out what dimension of the text to apply to the alternative font, keeping the x-height unchanged.
How to build it
The CSS syntax is pretty easy: font-size-adjust: number | none | inherit;
The possible values are the following:
■ number Defines the aspect ratio value to use
■ none The default value
■ inherit Inherits the font size adjustment from parent elements
You might be wondering how the aspect ratio value is calculated. The W3C specifications are very clear and provide a simple way of carrying out this calculation:
To make their display uniform, we need the font-size-adjust attribute: