diff --git a/src/components/SlideViewer.tsx b/src/components/SlideViewer.tsx
index 0a7e0a4f..0433ddbd 100644
--- a/src/components/SlideViewer.tsx
+++ b/src/components/SlideViewer.tsx
@@ -2098,6 +2098,53 @@ class SlideViewer extends React.Component<SlideViewerProps, SlideViewerState> {
     })
   }
 
+  /**
+   * Keep the side-panel segment switch in sync when the overlay's visibility
+   * is toggled from the in-viewport legend (dicom-microscopy-viewer already
+   * applied the change, so we only mirror it into component state).
+   */
+  onSegmentVisibilityChanged = (event: CustomEventInit): void => {
+    const detail = event.detail as
+      | { segmentUID?: string; isVisible?: boolean }
+      | undefined
+    if (detail?.segmentUID == null || detail.isVisible == null) {
+      return
+    }
+    const { segmentUID, isVisible } = detail
+    this.setState((state) => {
+      const visibleSegmentUIDs = new Set(state.visibleSegmentUIDs)
+      if (isVisible) {
+        visibleSegmentUIDs.add(segmentUID)
+      } else {
+        visibleSegmentUIDs.delete(segmentUID)
+      }
+      return { visibleSegmentUIDs }
+    })
+  }
+
+  /**
+   * Keep the side-panel mapping switch in sync when the overlay's visibility
+   * is toggled from the in-viewport legend.
+   */
+  onMappingVisibilityChanged = (event: CustomEventInit): void => {
+    const detail = event.detail as
+      | { mappingUID?: string; isVisible?: boolean }
+      | undefined
+    if (detail?.mappingUID == null || detail.isVisible == null) {
+      return
+    }
+    const { mappingUID, isVisible } = detail
+    this.setState((state) => {
+      const visibleMappingUIDs = new Set(state.visibleMappingUIDs)
+      if (isVisible) {
+        visibleMappingUIDs.add(mappingUID)
+      } else {
+        visibleMappingUIDs.delete(mappingUID)
+      }
+      return { visibleMappingUIDs }
+    })
+  }
+
   onLoadingStarted = (_event: CustomEventInit): void => {
     this.setState({ isLoading: true })
   }
@@ -2270,6 +2317,14 @@ class SlideViewer extends React.Component<SlideViewerProps, SlideViewerState> {
       'dicommicroscopyviewer_frame_loading_ended',
       this.onFrameLoadingEnded,
     )
+    document.body.removeEventListener(
+      'dicommicroscopyviewer_segment_visibility_changed',
+      this.onSegmentVisibilityChanged,
+    )
+    document.body.removeEventListener(
+      'dicommicroscopyviewer_parameter_mapping_visibility_changed',
+      this.onMappingVisibilityChanged,
+    )
     document.body.removeEventListener('keyup', this.onKeyUp)
     document.body.removeEventListener('keyup', this.onKeyDown)
     window.removeEventListener('resize', this.onWindowResize)
@@ -2398,6 +2453,14 @@ class SlideViewer extends React.Component<SlideViewerProps, SlideViewerState> {
       'dicommicroscopyviewer_frame_loading_error',
       this.onFrameLoadingError,
     )
+    document.body.addEventListener(
+      'dicommicroscopyviewer_segment_visibility_changed',
+      this.onSegmentVisibilityChanged,
+    )
+    document.body.addEventListener(
+      'dicommicroscopyviewer_parameter_mapping_visibility_changed',
+      this.onMappingVisibilityChanged,
+    )
     document.body.addEventListener('keyup', this.onKeyUp)
     document.body.addEventListener('keydown', this.onKeyDown)
     window.addEventListener('beforeunload', this.componentCleanup)
diff --git a/src/utils/distinctOverlayColormaps.ts b/src/utils/distinctOverlayColormaps.ts
index 69867989..0627d861 100644
--- a/src/utils/distinctOverlayColormaps.ts
+++ b/src/utils/distinctOverlayColormaps.ts
@@ -3,21 +3,18 @@ import * as dmv from 'dicom-microscopy-viewer'
 
 import { getSegmentationType, getSegmentColor } from './segmentColors'
 
-const COLORMAP_ORDER = [
-  dmv.color.ColormapNames.VIRIDIS,
-  dmv.color.ColormapNames.MAGMA,
-  dmv.color.ColormapNames.INFERNO,
-  dmv.color.ColormapNames.HOT,
-  dmv.color.ColormapNames.BLUE_RED,
-  dmv.color.ColormapNames.GRAY,
-  dmv.color.ColormapNames.PHASE,
-  dmv.color.ColormapNames.PORTLAND,
-] as const
-
-function buildPaletteForName(
-  name: (typeof COLORMAP_ORDER)[number],
+/**
+ * Build a perceptually distinct, single-hue palette for the overlay at
+ * `index`. Multi-hue scientific color maps (viridis, magma, inferno, hot, …)
+ * all share a dark → bright-yellow ramp and are therefore hard to tell apart
+ * and to match against the legend; single-hue ramps give each overlay a
+ * clearly different, easily named color.
+ * See https://github.com/ImagingDataCommons/dicom-microscopy-viewer/issues/240.
+ */
+function buildDistinctPalette(
+  index: number,
 ): dmv.color.PaletteColorLookupTable {
-  const data = dmv.color.createColormap({ name, bins: 2 ** 8 })
+  const data = dmv.color.createDistinctColormap({ index, bins: 2 ** 8 })
   return dmv.color.buildPaletteColorLookupTable({
     data,
     firstValueMapped: 0,
@@ -56,9 +53,8 @@ export function applyDistinctFractionalSegmentPalettes(
       return
     }
 
-    const name = COLORMAP_ORDER[paletteIndex % COLORMAP_ORDER.length]
+    const table = buildDistinctPalette(paletteIndex)
     paletteIndex += 1
-    const table = buildPaletteForName(name)
     const style = volumeViewer.getSegmentStyle(seg.uid)
     volumeViewer.setSegmentStyle(seg.uid, {
       opacity: style.opacity,
@@ -79,8 +75,7 @@ export function applyDistinctParametricMapPalettes(
   }
 
   mappings.forEach((mapping, i) => {
-    const name = COLORMAP_ORDER[i % COLORMAP_ORDER.length]
-    const table = buildPaletteForName(name)
+    const table = buildDistinctPalette(i)
     const style = volumeViewer.getParameterMappingStyle(mapping.uid)
     volumeViewer.setParameterMappingStyle(mapping.uid, {
       opacity: style.opacity,
diff --git a/types/dicom-microscopy-viewer/index.d.ts b/types/dicom-microscopy-viewer/index.d.ts
index 47a29b64..e13032fd 100644
--- a/types/dicom-microscopy-viewer/index.d.ts
+++ b/types/dicom-microscopy-viewer/index.d.ts
@@ -803,6 +803,11 @@ declare module 'dicom-microscopy-viewer' {
       bins: number
     }): number[][]
 
+    export function createDistinctColormap (options: {
+      index: number
+      bins: number
+    }): number[][]
+
     export interface PaletteColorLookupTableOptions {
       uid: string
       redDescriptor: number[]