CSS Corner: Using the Whole Font

With cross-browser support for both the CSS3 @font-face rule and the WOFF font packaging format, modern Web typography has expanded far beyond the realm of ‘Web-safe fonts.’ Well-known magazines such as the New Yorker use Web fonts to preserve the typographic personality of their headlines, while [US] President Obama’s re-election campaign uses Web font service Typekit to host their identity font.

One remaining limitation prevents Web designers from using the entire font: the inability to access the large variety of optional OpenType® features built into many fonts. These features define glyph substitution and positioning options to support fundamental typographical features such as kerning, superscript and subscript, contextual letterforms such as ligatures, numeral styles, access to alternate East Asian glyphs as well as ornamental swashes.

For instance, an OpenType “stylistic set” built into Gabriola allows this text:

String of text in Gabriola font without stylistic sets applied

…to render as:

String of text in Gabriola font with stylistic set 6 applied

Recent updates to the CSS3 Fonts module include a new set of properties to expose these OpenType features within CSS. These properties can be grouped in two broad categories:

  • An explicit mapping of the common OpenType features to specific properties and values. For example font-kerning:normal applies the kerning pair adjustments encoded within the font and font-variant-numeric: tabular-nums enables tabular numerals.
  • The font-feature-settings property enables low-level access to all the OpenType features supported by a font. It is meant as an ‘escape hatch’ to access to more advanced features in less common use-cases.

CSS Property: font-feature-settings

Preview 4 of IE10 includes support for the font-feature-settings property. Our earlier Gabriola example could thus be written:

p#demo {

font-family: Gabriola, cursive;

font-size: 24pt;

-ms-font-feature-settings: "ss06" 1;


The -ms-font-feature-settings declaration above turns on a stylistic set supported by the font (ss06). The property takes either a value of ‘normal’ – no change in glyph selection or positioning – or a comma-separated list of one or more features. Each feature combines a four-letter OpenType feature tag and a value. In the example above, “ss06” is the OpenType feature tag for stylistic set 6. We assign the value 1 to the feature to turn it on.

The OpenType feature registry defines the list of possible tags (also documented here and standardized by ISO). Here a few of the most popular:

OpenType tag Enables
kern Kerning
liga Standard ligatures
dlig Discretionary ligatures
smcp Small capitals
subs Subscript
sups Superscript
swsh Swashes
ss01, ss02, …, ss20 Stylistic sets 1 to 20

For a good illustrated introduction to these features and many others, we recommend the Layout Features section of the FontFont OpenType User Guide.

The more common features are on/off switches. Feature values of off or zero turn the feature off; a value of on or any positive integer activates it. For some features, an integer value gives access to several options. This is usually the case for swashes (‘swsh’). If no value is specified for the feature, a value of 1 is assumed. All the following declarations are thus equivalent for the purpose of our Gabriola example:

-ms-font-feature-settings: "ss06" 1;

-ms-font-feature-settings: "ss06" on;

-ms-font-feature-settings: "ss06";

Finding Out Supported Features for a Font

Design tools such as Adobe InDesign or Illustrator expose OpenType features through user-friendly menus and dialogs, word processors such as Word support them through their font selection dialog and font vendors often document which features their products support. A future post will discuss using the browser to detect font features. With more browser access to OpenType features we expect font hosting services to do more to advertise and document their use as well.

Browser Support

The font-feature-settings property is currently supported by Firefox 4+ and Internet Explorer 10, beginning with Preview 4. Note that because Firefox and IE implemented different versions of the draft the value syntax they accept is different. For example, enabling kerning in both browsers requires the following:

-ms-font-feature-settings: "kern" 1;

-moz-font-feature-setting: "kern=1";

More information about –moz-font-feature-settings see -moz-font-feature-settings.

As CSS3 Fonts moves along the standardization track we expect more browsers to add support for font-feature-setttings as well as the more author-friendly font-variant properties and values defined in the module.

Also note that the property applies to all font families, whether Web fonts downloaded through @font-face rules or local fonts referenced by name.


Our IE Test Drive site includes advanced OpenType feature demos from Monotype Imaging, FontFont and The Font Bureau. They demonstrate the variety of typographic designs available in modern fonts.

You don’t need any special fonts to try this. Windows 7 includes a number of OpenType-enabled fonts including Calibri, Cambria, Consolas, Gabriola, and Palatino Linotype. In the Windows 8 Developer Preview, we added OpenType features to Segoe UI and the Web-safe fonts Arial, Verdana, Georgia, Times New Roman, Comic Sans and Trebuchet.

We are excited to give Web authors access to all the OpenType features built in Web fonts and look forward to an even broader range of typographic design on the Web.

—Sylvain Galineau, Program Manager, Internet Explorer