diff --git a/e2e/tests/journeys.spec.ts b/e2e/tests/journeys.spec.ts
index 1fee453..d4cc865 100644
--- a/e2e/tests/journeys.spec.ts
+++ b/e2e/tests/journeys.spec.ts
@@ -228,7 +228,12 @@ test('compare chart on mobile shows school chips with tap-to-focus', async ({ pa
   expect(bodyOverflowsX).toBe(false);
 
   // The trends chart still renders (inside the Explore trends section)…
-  await expect(page.locator('canvas:visible').first()).toBeVisible({ timeout: 15_000 });
+  const chartCanvas = page.locator('canvas:visible').first();
+  await expect(chartCanvas).toBeVisible({ timeout: 15_000 });
+  // …at a real height, not the squashed ~150px Chart.js fallback that
+  // appears when the container lacks a definite height.
+  const chartBox = await chartCanvas.boundingBox();
+  expect(chartBox && chartBox.height).toBeGreaterThan(220);
 
   // …with the mobile chart legend chips and tap-to-focus behaviour intact.
   const chipGroup = page.getByRole('group', { name: /highlight a school/i });
diff --git a/nextjs-app/components/compare/TrendsExplorer.module.css b/nextjs-app/components/compare/TrendsExplorer.module.css
index d6ddd4d..61f17fa 100644
--- a/nextjs-app/components/compare/TrendsExplorer.module.css
+++ b/nextjs-app/components/compare/TrendsExplorer.module.css
@@ -60,8 +60,20 @@
   margin: 0 0 1rem;
 }
 
+/* ComparisonChart runs Chart.js with maintainAspectRatio:false, so it fills
+   its container's height — which must be *definite*. A min-height alone does
+   not resolve the chart wrapper's height:100%, leaving Chart.js to fall back
+   to its ~150px default (a squashed sliver). Give it a real height. */
 .chartBox {
-  min-height: 320px;
+  height: 420px;
+}
+
+@media (max-width: 640px) {
+  /* Taller on mobile: the mobile-only school chips sit above the canvas and
+     wrap to two rows for 3+ schools, so the plot keeps a usable height. */
+  .chartBox {
+    height: 360px;
+  }
 }
 
 .tableWrapper {