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  <title>Area chart with gradient</title>
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    # Area chart with gradient

    A custom [function mark](https://observablehq.com/plot/features/marks) returns a svg gradient (generated with [Hypertext Literal](https://github.com/observablehq/htl)), that can be referenced as a [funciri](https://developer.mozilla.org/en-US/docs/Web/SVG/Content_type#funciri) color in the [area](https://observablehq.com/plot/marks/area) mark.
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