data:text/html,<div style="font: 24px DejaVu Serif; letter-spacing: 10px; font-variant: common-ligatures">office
This renders with an "ffi" ligature in Firefox, even though the presence of
letter-spacing should cause common ligatures to be disabled, according to the spec:
General and font specific font feature property settings are resolved in the order below, in ascending order of precedence. This ordering is used to construct a combined list of font features that affect a given text run.
- Font features enabled by default, including features required for a given script.
- If the font is defined via an @font-face rule, the font features implied by the font-feature-settings descriptor in the @font-face rule.
- Font features implied by the value of the ‘font-variant’ property, the related ‘font-variant’ subproperties and any other CSS property that uses OpenType features (e.g. the ‘font-kerning’ property).
- Feature settings determined by properties other than ‘font-variant’ or ‘font-feature-settings’. For example, setting a non-default value for the ‘letter-spacing’ property disables common ligatures.
- Font features implied by the value of ‘font-feature-settings’ property.
We implement the disabling of ligatures due to non-default
letter-spacing, but we do this too early in feature resolution, and the
font-variant: common-ligatures property then overrides it. Only
font-feature-settings should be able to do this.
As a result, we fail several of the examples in web-platform/tests/css/css-fonts/font-feature-resolution-001.html.