diff --git a/plugin-designs/gospel-internet/board.vue b/plugin-designs/gospel-internet/board.vue
index a66d3a059..fa67bff25 100644
--- a/plugin-designs/gospel-internet/board.vue
+++ b/plugin-designs/gospel-internet/board.vue
@@ -39,6 +39,7 @@ import GiDrawer from './src/components/GiDrawer.vue'
 import GiTree from './src/components/GiTree.vue'
 import GiResources from './src/components/GiResources.vue'
 import GiCombos from './src/components/GiCombos.vue'
+import { isNarrowWidth } from './src/breakpoints.js'
 
 const T = useGiT()
 const board = useBoard()
@@ -76,7 +77,7 @@ board.readUrl()
 // partner's address bar is never rewritten. facetKeys is explicit: its default reads nothing on a cold load.
 useShareableView(bus, { mode: 'query', write: board.profileConfig.value?.urlState === 'query', facetKeys: SHARE_FACETS })
 
-// ── responsive: one panel at a time under 760px (ResizeObserver on the shell, not @container: a
+// ── responsive: one panel at a time under the shared breakpoint (ResizeObserver on the shell, not @container: a
 // container query cannot target the container itself, which is unreliable inside a shadow root) ──────
 const shell = ref(null)
 const isNarrow = ref(false)
@@ -84,7 +85,7 @@ const mobilePanel = ref('map')
 let ro = null
 onMounted(() => {
   if (shell.value && typeof ResizeObserver !== 'undefined') {
-    ro = new ResizeObserver(([e]) => { isNarrow.value = e.contentRect.width < 760 })
+    ro = new ResizeObserver(([e]) => { isNarrow.value = isNarrowWidth(e.contentRect.width) })
     ro.observe(shell.value)
   }
   board.load()
diff --git a/plugin-designs/gospel-internet/src/breakpoints.js b/plugin-designs/gospel-internet/src/breakpoints.js
new file mode 100644
index 000000000..61bdaefc2
--- /dev/null
+++ b/plugin-designs/gospel-internet/src/breakpoints.js
@@ -0,0 +1,18 @@
+/**
+ * breakpoints.js — the one width at which this dashboard stops being a three-column board.
+ *
+ * ★ IT IS A CONSTANT BECAUSE IT WAS TWO NUMBERS. board.vue collapsed to a single panel below
+ * 760px; the set charts stacked their legend below 900px. Between those two widths the board
+ * still held three columns while a chart inside it had already given up on having room — at
+ * 768 the centre column was about 145px, so the bounded figure was crushed to 124px and the
+ * centered figure's own minimum made it spill UNDER the right-hand panel.
+ *
+ * Neither number was wrong on its own. The defect was that they were separate, and nothing
+ * connected the width at which a chart needs room to the width at which the board gives it any.
+ */
+export const NARROW_MAX = 900
+
+/** True when the shell is too narrow for side panels beside the centre column. */
+export function isNarrowWidth(px) {
+  return Number(px) < NARROW_MAX
+}
diff --git a/plugin-designs/gospel-internet/src/components/GiCenteredSet.vue b/plugin-designs/gospel-internet/src/components/GiCenteredSet.vue
index 357037f7c..6dacd7a40 100644
--- a/plugin-designs/gospel-internet/src/components/GiCenteredSet.vue
+++ b/plugin-designs/gospel-internet/src/components/GiCenteredSet.vue
@@ -28,6 +28,7 @@ import { layoutCenteredSet, ringTally, inwardArrow, ringRadii } from '@map/compo
 import GiRingLegend from './GiRingLegend.vue'
 import GiCenteredSetMap from './GiCenteredSetMap.vue'
 import FullscreenButton from '@map/components/map-controls/FullscreenButton.vue'
+import { NARROW_MAX } from '../breakpoints.js'
 
 const T = useGiT()
 const board = useBoardState()
@@ -70,7 +71,10 @@ function applyWidth(m) {
 function setLegendOpen(v) { chosen = v; legendOpen.value = v }
 onMounted(() => {
   try {
-    mq = window.matchMedia('(max-width: 900px)')
+    // The same width the BOARD collapses at (NARROW_MAX). If these two ever disagree again,
+    // the board keeps its side panels while the chart has already given up on room — which is
+    // exactly the 768px failure.
+    mq = window.matchMedia(`(max-width: ${NARROW_MAX - 1}px)`)
     applyWidth(mq)
     mq.addEventListener?.('change', applyWidth)
   } catch (_) { /* no matchMedia: stay wide, which is the layout that always fits */ }