The <system-color>
CSS data type usually reflects the default color choices used for the different parts of a web page.
However, user agents can provide an accessibility feature called forced colors mode, in which colors are restricted into a user- and user agent-defined palette, overriding the author's choice of colors in certain properties. In forced colors mode, <system-color>
exposes the chosen colors, so that the rest of the page can integrate with them. An example of forced colors mode is high contrast mode on Windows.
In forced colors mode, authors should use colors from the <system-color>
type for all properties that are not in the set of properties whose colors are overridden. This ensures that the page consistently uses the same color palette across all properties.
Authors can detect forced colors mode using the forced-colors
media feature.
A <system-color>
value can be used anywhere a <color>
can be used.