The <<.def colour>> (or <<.def color>>) [[macro|Macros]] returns the [[CSS|Cascading Style Sheets]] value of one the colours in the current [[palette|ColourPalettes]].
If no such entry exists in the current palette, the [[vanilla palette|$:/palettes/Vanilla]] is used instead. If no such entry exists in the vanilla palette, the system looks for a configuration tiddler with the title `$:/config/DefaultColourMappings/<colour-name>` and transcludes the colour from the text field. This enables to plugins to ship defaults for colours that are not present in the core palettes.
