Area Chart

Show volume or composition under a trend line with filled regions.

Area charts share the line-series model: each series carries numeric values and optional stack_group ids. Turn on stacked or percent modes when the story is about contribution, not just the stroke.

• Cumulative or stacked metrics where filled regions reinforce magnitude.
• Normalized (100%) stacks when share-of-whole matters — set stack_offset: Expand.
• Monthly or quarterly trends with multiple contributing series.

• Assign the same stack_group on series you want stacked per category.
• Set stack_offset on the chart or any series member — Expand normalizes to 100%.
• Enable legend and tooltip via cross-cutting previews (charts-legend, charts-tooltip).
• Leave skip_animation unset to honor reduced-motion preferences.
• Wrap the chart in a native element with data-testid for E2E hooks.