diff --git a/client/src/components/Map/MapViewGL.test.tsx b/client/src/components/Map/MapViewGL.test.tsx
index a8262dc4d..550e14a9b 100644
--- a/client/src/components/Map/MapViewGL.test.tsx
+++ b/client/src/components/Map/MapViewGL.test.tsx
@@ -942,6 +942,24 @@ describe('MapViewGL', () => {
     expect(glMarkers.created).toHaveLength(before)
   })
 
+  it.each([
+    ['mapbox-gl', () => mapboxgl.Popup],
+    ['maplibre-gl', () => maplibregl.Popup],
+  ] as const)('FE-COMP-MAPVIEWGL-068: the %s hover card clears its marker without a tail', async (provider, popupOf) => {
+    loadOnAttach()
+    const { unmount } = render(<MapViewGL places={[]} fitKey={1} glProvider={provider} />)
+    await act(async () => {})
+
+    // The tail is hidden in index.css, and it used to contribute 10px of the
+    // gap itself — the offset has to make those up or the card sits on top of
+    // the marker it describes.
+    const options = (popupOf() as unknown as { mock: { calls: [Record<string, unknown>][] } }).mock.calls[0]?.[0]
+    expect(options).toMatchObject({ className: 'trek-map-popup', offset: 26, closeButton: false })
+    // Leaves the map listeners attached otherwise, and the next case reads them
+    // back out of the same mock.
+    unmount()
+  })
+
   it('FE-COMP-MAPVIEWGL-027: clicking a GPX track selects its place unless a marker or cluster is on top', async () => {
     loadOnAttach()
     const onMarkerClick = vi.fn()
diff --git a/client/src/components/Map/mapPopupCss.test.ts b/client/src/components/Map/mapPopupCss.test.ts
new file mode 100644
index 000000000..80cd7a4f6
--- /dev/null
+++ b/client/src/components/Map/mapPopupCss.test.ts
@@ -0,0 +1,37 @@
+import { readFileSync } from 'node:fs'
+import { resolve } from 'node:path'
+import { describe, it, expect } from 'vitest'
+
+// The GL map's hover card is styled from index.css while its geometry comes
+// from the vendor stylesheet, so the two only agree by convention. These read
+// the real files rather than a rendered component: jsdom applies no vendor CSS,
+// which is exactly the interaction that can break here.
+describe('GL hover popup css', () => {
+  // Vitest runs with the client package as its root, so cwd is stable here.
+  const css = readFileSync(resolve(process.cwd(), 'src/index.css'), 'utf8')
+  const block = (selector: string): string => {
+    const at = css.indexOf(selector)
+    expect(at, `${selector} missing from index.css`).toBeGreaterThan(-1)
+    return css.slice(at, css.indexOf('}', at) + 1)
+  }
+
+  it('FE-COMP-MAPPOPUPCSS-001: the tail is off, not merely painted white', () => {
+    // Colouring it left a visible notch under the card in every theme.
+    expect(block('.trek-map-popup .maplibregl-popup-tip')).toMatch(/display:\s*none/)
+  })
+
+  it('FE-COMP-MAPPOPUPCSS-002: the corner radius outweighs the vendor anchor rules', () => {
+    // maplibre-gl.css squares one corner per anchor so the tail meets the card
+    // flush. With the tail gone that is just a squared corner, and the vendor
+    // rule carries the same specificity as a plain `.trek-map-popup .content`
+    // — whichever sheet loads last would win. The `[class]` guard settles it.
+    const radius = block('.trek-map-popup[class] .maplibregl-popup-content')
+    expect(radius).toMatch(/border-radius:\s*10px/)
+  })
+
+  it('FE-COMP-MAPPOPUPCSS-003: leaflet click popups keep their tail', () => {
+    // Those are anchored, dismissable popups where the tail earns its place —
+    // the fix above is scoped to the GL hover card on purpose.
+    expect(block('.leaflet-popup-tip')).not.toMatch(/display:\s*none/)
+  })
+})
diff --git a/client/src/index.css b/client/src/index.css
index 9f6c4ce3b..23b477fc2 100644
--- a/client/src/index.css
+++ b/client/src/index.css
@@ -46,14 +46,23 @@ body { height: 100%; overflow: auto; overscroll-behavior: none; -webkit-overflow
   background: #fff;
   box-shadow: 0 2px 12px rgba(0, 0, 0, 0.16);
 }
-/* No speech-bubble tail on the hover card. It is a label that follows the
-   cursor onto whatever it is over, not a popup anchored to one spot, and the
-   tail read as a stray notch hanging off the bottom edge. The popup's own
-   offset carries the gap to the marker instead. */
+/* No speech-bubble tail on the hover card. The card stands off its marker by
+   26px and reads as a label, not as a callout pinned to a point — the tail
+   hung off the bottom edge as a stray notch. The popup's offset carries the
+   gap on its own. */
 .trek-map-popup .mapboxgl-popup-tip,
 .trek-map-popup .maplibregl-popup-tip {
   display: none;
 }
+/* Both engines square off one corner per anchor so the tail meets the card
+   flush (.maplibregl-popup-anchor-bottom-left .maplibregl-popup-content and
+   its three siblings). Same specificity as the rule above, so which one wins
+   comes down to stylesheet order — and with no tail there, a squared corner is
+   just a squared corner. `[class]` buys the extra weight to settle it. */
+.trek-map-popup[class] .mapboxgl-popup-content,
+.trek-map-popup[class] .maplibregl-popup-content {
+  border-radius: 10px;
+}
 
 .atlas-tooltip {
   background: rgba(10, 10, 20, 0.6) !important;