Stylistic set
A switch in an OpenType font that replaces a coordinated group of letters or symbols with alternate drawings.
See it
What it is
A stylistic set is a coordinated group of alternate glyphs stored in an OpenType font. Turning on one feature, tagged 'ss01' through 'ss20', can swap several related letterforms at once so the alphabet keeps a consistent voice. A set might replace a double-story a and g with single-story forms, straighten a hooked l, or change a group of punctuation marks together.
Reach for a set when the default drawing is wrong for the job but a different typeface would be overkill. Design tools already expose them: InDesign lists Stylistic Sets under the Character panel's OpenType menu, and Figma shows the available features in the type details panel. Enable it in CSS with 'font-feature-settings: "ss01"' after checking the font's specimen or GSUB table. Use it consistently across the relevant text rather than picking alternate letters one by one and accidentally mixing design systems.
Gotcha: 'ss01' has no universal visual meaning. It can produce an alternate a in one font, different numerals in another, and nothing in a third. The characters in the document do not change, only their glyphs do. Subsetting can also remove the alternates or GSUB lookup, so test the final webfont rather than the full desktop source.
Ask AI for it
Build a stylistic-set tester for the supplied OpenType font. Inspect its GSUB table with fontTools and list only the 'ss01' through 'ss20' features that actually exist, including any feature names stored in the font. Render the same specimen beside each toggle and apply the selected tag with 'font-feature-settings', preserving the full active tag list whenever a toggle changes. Include a, g, l, R, Q, numerals, and punctuation in the specimen, and verify the subsetted WOFF2 keeps the same glyph substitutions before shipping it.