diff --git a/reactapp/__tests__/components/dashboard/DashboardItem.test.js b/reactapp/__tests__/components/dashboard/DashboardItem.test.js
index 721a45f2..3c2ad5f0 100644
--- a/reactapp/__tests__/components/dashboard/DashboardItem.test.js
+++ b/reactapp/__tests__/components/dashboard/DashboardItem.test.js
@@ -5,6 +5,7 @@ import {
   within,
   fireEvent,
   waitFor,
+  cleanup,
 } from "@testing-library/react";
 import DashboardItem, {
   handleGridItemExport,
@@ -1655,6 +1656,97 @@ test("Dashboard attribution and not show", async () => {
   ).not.toBeInTheDocument();
 });
 
+// jsdom's computed style does not resolve :has(), so the raise cannot be read
+// back through getComputedStyle. Inspecting the injected rule is the next best
+// thing: it pins that the rule ships, what it raises to, and that it is scoped to
+// the fill-viewport branch rather than applied to every grid item.
+const injectedCss = () =>
+  Array.from(document.styleSheets)
+    .flatMap((sheet) => {
+      try {
+        return Array.from(sheet.cssRules).map((rule) => rule.cssText);
+      } catch {
+        return [];
+      }
+    })
+    .join("\n");
+
+const raiseRule = () =>
+  injectedCss()
+    .split("\n")
+    .find((rule) => rule.includes('data-map-control-open="true"'));
+
+// The class styled-components generated for the fill-viewport block. Asserting
+// class membership on the element is order-independent, unlike asserting the rule
+// is absent from the stylesheet -- styled-components keeps injected rules for the
+// whole test file, so a rule from an earlier test is still present.
+const raiseRuleClass = () => {
+  const rule = raiseRule();
+  const match = rule && rule.match(/^\.([\w-]+)/);
+  return match ? match[1] : null;
+};
+
+const renderGridItem = ({ fillViewport }) => {
+  const mockedDashboard = JSON.parse(JSON.stringify(userDashboard));
+  const gridItem = mockedDashboard.tabs[0].gridItems[0];
+  gridItem.metadata_string = JSON.stringify(
+    fillViewport ? { fillViewport: true } : {},
+  );
+
+  return render(
+    createLoadedComponent({
+      children: (
+        <GridItemContext.Provider
+          value={{
+            gridItemSource: gridItem.source,
+            gridItemI: gridItem.i,
+            gridItemMetadataString: gridItem.metadata_string,
+            gridItemArgsString: gridItem.args_string,
+            gridItemIndex: 0,
+            enableFillViewport: true,
+          }}
+        >
+          <DashboardItem />
+        </GridItemContext.Provider>
+      ),
+      options: { initialDashboard: mockedDashboard },
+    }),
+  );
+};
+
+test("Dashboard Item fill viewport raises the tile for an open map control", async () => {
+  // position:fixed seals the item into its own stacking context, so a map's
+  // legend or layer control cannot paint above a later grid item on its own.
+  renderGridItem({ fillViewport: true });
+  const item = await screen.findByLabelText("gridItemDiv");
+
+  const rule = raiseRule();
+  expect(rule).toBeDefined();
+  expect(rule).toMatch(/z-index:\s*1029/);
+  // Below the fixed header and every modal layer, so a modal still covers the map.
+  expect(rule).not.toMatch(/z-index:\s*10[4-9]\d/);
+  // And the rule actually applies to this item.
+  expect(item.classList.contains(raiseRuleClass())).toBe(true);
+});
+
+test("Dashboard Item without fill viewport is not covered by the raise rule", async () => {
+  // A non-fill item is position:relative / z-index:auto, so it is not a stacking
+  // context and the control's own z-index already escapes. Scoping the rule to
+  // the fill branch keeps that path untouched.
+  renderGridItem({ fillViewport: true });
+  await screen.findByLabelText("gridItemDiv");
+  const fillClass = raiseRuleClass();
+  expect(fillClass).not.toBeNull();
+  cleanup();
+
+  renderGridItem({ fillViewport: false });
+  const item = await screen.findByLabelText("gridItemDiv");
+  expect(window.getComputedStyle(item).getPropertyValue("position")).toBe(
+    "relative",
+  );
+  expect(item.classList.contains(fillClass)).toBe(false);
+});
+
 test("Dashboard Item fill viewport fills the content area in view mode", async () => {
   const mockedDashboard = JSON.parse(JSON.stringify(userDashboard));
   const gridItem = mockedDashboard.tabs[0].gridItems[0];
diff --git a/reactapp/__tests__/components/map/LayersControl.test.js b/reactapp/__tests__/components/map/LayersControl.test.js
index 02fe2b27..daffb54c 100644
--- a/reactapp/__tests__/components/map/LayersControl.test.js
+++ b/reactapp/__tests__/components/map/LayersControl.test.js
@@ -251,3 +251,24 @@ describe("parseProgress", () => {
     expect(parseProgress(message)).toBeNull();
   });
 });
+
+test("LayersControl flags itself only while expanded", async () => {
+  render(
+    <LayersControl updater={null} visualizationRef={{ current: undefined }} />,
+  );
+
+  expect(screen.getByLabelText("Layers Control")).not.toHaveAttribute(
+    "data-map-control-open",
+  );
+
+  fireEvent.click(await screen.findByLabelText("Show Layers Control"));
+  expect(screen.getByLabelText("Layers Control")).toHaveAttribute(
+    "data-map-control-open",
+    "true",
+  );
+
+  fireEvent.click(await screen.findByLabelText("Close Layers Control"));
+  expect(screen.getByLabelText("Layers Control")).not.toHaveAttribute(
+    "data-map-control-open",
+  );
+});
diff --git a/reactapp/__tests__/components/map/Legend.test.js b/reactapp/__tests__/components/map/Legend.test.js
index 42f04a0c..a0af313d 100644
--- a/reactapp/__tests__/components/map/Legend.test.js
+++ b/reactapp/__tests__/components/map/Legend.test.js
@@ -44,3 +44,21 @@ test("LegendControl", async () => {
   fireEvent.click(closeLegendButton);
   expect(screen.queryByText("Some New Title")).not.toBeInTheDocument();
 });
+
+test("LegendControl flags itself only while expanded", async () => {
+  // The flag is what DashboardItem's fill-viewport rule keys off to raise the
+  // whole tile. Raising the tile is the only lever available: position:fixed
+  // makes it a stacking context, so no z-index on the control can escape it.
+  render(<LegendControl legendItems={[legendItems]} />);
+
+  fireEvent.click(await screen.findByLabelText("Show Legend Control"));
+  expect(await screen.findByLabelText("Legend Control")).toHaveAttribute(
+    "data-map-control-open",
+    "true",
+  );
+
+  fireEvent.click(await screen.findByLabelText("Close Legend Control"));
+  expect(screen.getByLabelText("Legend Control")).not.toHaveAttribute(
+    "data-map-control-open",
+  );
+});
diff --git a/reactapp/__tests__/components/visualizations/Card.test.js b/reactapp/__tests__/components/visualizations/Card.test.js
index c52b5384..fc827938 100644
--- a/reactapp/__tests__/components/visualizations/Card.test.js
+++ b/reactapp/__tests__/components/visualizations/Card.test.js
@@ -48,6 +48,40 @@ it("Creates a Card with a Title and Description", () => {
   expect(screen.getByText("Fake Description")).toBeInTheDocument();
 });
 
+it("Omits the header entirely when a plugin returns neither title nor description", async () => {
+  // Both are optional in the `card` return shape. Rendering them unguarded left
+  // an empty heading, an empty paragraph and Header's 1.5rem margin above the
+  // stats for any plugin that returns only `data`.
+  const { data } = mockedCardData;
+  initAndRender({ data });
+
+  // The stats render behind Suspense, so wait for them before concluding the
+  // header is absent rather than merely not painted yet.
+  expect(await screen.findByText("Total Sales")).toBeInTheDocument();
+  expect(screen.getByText("1,500")).toBeInTheDocument();
+  expect(screen.queryByRole("heading")).not.toBeInTheDocument();
+  // Not merely empty: the wrapper itself must go, or its 1.5rem margin stays.
+  expect(screen.queryByTestId("card-header")).not.toBeInTheDocument();
+});
+
+it("Renders only the title when no description is given", () => {
+  initAndRender({ title: "Fake Title", data: [] });
+
+  expect(
+    screen.getByRole("heading", { name: "Fake Title" }),
+  ).toBeInTheDocument();
+  expect(screen.queryByText("Fake Description")).not.toBeInTheDocument();
+});
+
+it("Renders only the description when no title is given", () => {
+  // The case the inner title guard exists for: the header is rendered because a
+  // description is present, so without the guard an empty <h3> comes with it.
+  initAndRender({ description: "Fake Description", data: [] });
+
+  expect(screen.getByText("Fake Description")).toBeInTheDocument();
+  expect(screen.queryByRole("heading")).not.toBeInTheDocument();
+});
+
 it("Creates a Card with actual data", async () => {
   const { title, data } = mockedCardData;
   initAndRender({
diff --git a/reactapp/__tests__/components/visualizations/DataTable.test.js b/reactapp/__tests__/components/visualizations/DataTable.test.js
index 20efa37d..3d27da85 100644
--- a/reactapp/__tests__/components/visualizations/DataTable.test.js
+++ b/reactapp/__tests__/components/visualizations/DataTable.test.js
@@ -68,6 +68,28 @@ it("Creates a Data Table with the provided data", () => {
   expect(occupationData3).toBeInTheDocument();
 });
 
+it("Omits the heading entirely when a plugin returns no title", () => {
+  // title is optional in the `table` return shape. Rendering it unguarded left
+  // an empty <h2> -- a heading's worth of blank space above the table -- for any
+  // plugin that returns only `data`.
+  const { title, ...withoutTitle } = mockedTableData;
+  initAndRender(withoutTitle);
+
+  expect(screen.queryByRole("heading")).not.toBeInTheDocument();
+  // The table itself still renders.
+  expect(screen.getByText("Name")).toBeInTheDocument();
+  expect(screen.getByText("Alice Johnson")).toBeInTheDocument();
+});
+
+it("Still renders the heading when a title is provided", () => {
+  const { subtitle, ...withTitle } = mockedTableData;
+  initAndRender({ ...withTitle, title: "User Information" });
+
+  expect(
+    screen.getByRole("heading", { name: "User Information" }),
+  ).toBeInTheDocument();
+});
+
 it("Creates a Data Table with subtitle with the provided data", () => {
   mockedTableData.subtitle = "some subtitle";
   initAndRender(mockedTableData);
diff --git a/reactapp/components/dashboard/DashboardItem.js b/reactapp/components/dashboard/DashboardItem.js
index d87a8586..99a56c18 100644
--- a/reactapp/components/dashboard/DashboardItem.js
+++ b/reactapp/components/dashboard/DashboardItem.js
@@ -78,6 +78,29 @@ const StyledDiv = styled.div`
       left: 0;
       width: 100vw;
       height: calc(100vh - (${props.$fillOffset}));
+
+      /* position:fixed creates a stacking context even at z-index:auto, which
+         seals everything inside this item in. A map's legend, layer control,
+         error alert and coordinate readout all set z-index:1000, but that only
+         orders them against each other, never against another grid item -- the
+         item paints as one unit in gridItems order, so a tile ordered after this
+         one covered the map's own controls. In edit mode the bug disappears
+         because fillViewportActive is gated on !isEditing, leaving the item
+         position:relative and therefore not a stacking context.
+
+         Raising the item while a control is open is the only way out: no
+         descendant z-index can escape a stacking context, so lifting the whole
+         subtree is the lever available. The trade is that an overlapping tile
+         ordered after this one is hidden for as long as the control is open. It
+         reverts on close, so the DOM-order layering described above still holds
+         the rest of the time.
+
+         1029 clears dropdowns (1000) and sticky (1020) but stays below the fixed
+         header (1030) and all modal chrome (backdrop 1040, modal 1050, popover
+         1070, tooltip 1080, app alerts 1081), so a modal still covers the map. */
+      &:has([data-map-control-open="true"]) {
+        z-index: 1029;
+      }
     `}
 `;
 
diff --git a/reactapp/components/map/LayersControl.js b/reactapp/components/map/LayersControl.js
index 64c24858..af60d4ad 100644
--- a/reactapp/components/map/LayersControl.js
+++ b/reactapp/components/map/LayersControl.js
@@ -160,7 +160,11 @@ const LayersControl = ({ updater, visualizationRef, runtimeLayerState }) => {
 
   return (
     <ControlWrapper>
-      <LayerControlContainer $isexpanded={isexpanded}>
+      <LayerControlContainer
+        $isexpanded={isexpanded}
+        aria-label="Layers Control"
+        data-map-control-open={isexpanded ? "true" : undefined}
+      >
         {isexpanded ? (
           <>
             <b>Map Layers</b>
diff --git a/reactapp/components/map/LegendControl.js b/reactapp/components/map/LegendControl.js
index 52556ce2..e72907ce 100644
--- a/reactapp/components/map/LegendControl.js
+++ b/reactapp/components/map/LegendControl.js
@@ -55,6 +55,7 @@ const LegendControl = ({ legendItems }) => {
           <LegendControlContainer
             $isexpanded={isexpanded}
             aria-label="Legend Control"
+            data-map-control-open={isexpanded ? "true" : undefined}
             className="legend-control"
           >
             {isexpanded ? (
diff --git a/reactapp/components/visualizations/Card.js b/reactapp/components/visualizations/Card.js
index ae6752e0..d69672a7 100644
--- a/reactapp/components/visualizations/Card.js
+++ b/reactapp/components/visualizations/Card.js
@@ -89,10 +89,15 @@ const StatItemGroup = ({ item, index }) => {
 const Card = ({ title, description, data, visualizationRef }) => {
   return (
     <CardContainer ref={visualizationRef}>
-      <Header>
-        <h3>{title}</h3>
-        <p>{description}</p>
-      </Header>
+      {/* Both are optional in the `card` return shape. Rendering them unguarded
+          left an empty heading and paragraph, and Header's own 1.5rem margin,
+          above the stats for any plugin that returns only `data`. */}
+      {(title || description) && (
+        <Header data-testid="card-header">
+          {title && <h3>{title}</h3>}
+          {description && <p>{description}</p>}
+        </Header>
+      )}
       {data.length === 0 ? (
         <StatItemGroup />
       ) : (
diff --git a/reactapp/components/visualizations/DataTable.js b/reactapp/components/visualizations/DataTable.js
index ac3b8835..b505fb4b 100644
--- a/reactapp/components/visualizations/DataTable.js
+++ b/reactapp/components/visualizations/DataTable.js
@@ -47,7 +47,10 @@ const DataTable = ({ data, title, subtitle, visualizationRef }) => {
 
   return (
     <StyledDiv>
-      <h2>{title}</h2>
+      {/* Guarded like the subtitle below it: title is optional in the `table`
+          return shape, and rendering an empty <h2> left a heading's worth of
+          blank space above the table for any plugin that omits one. */}
+      {title && <h2>{title}</h2>}
       {subtitle && <h4>{subtitle}</h4>}
       <Table striped bordered hover ref={visualizationRef}>
         <TableHead />