From e4565e9f158721d4df6b918f2b065de82851f8d9 Mon Sep 17 00:00:00 2001
From: Tudor <tudor@Tudors-MacBook-Pro.local>
Date: Tue, 14 Jul 2026 23:24:39 +0100
Subject: [PATCH] fix(compare): give the trends chart a real height (was
 squashed to ~150px)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

ComparisonChart runs Chart.js with maintainAspectRatio:false, so it sizes
to its container's height — which must be definite. TrendsExplorer gave
.chartBox a min-height, which doesn't resolve the chart wrapper's
height:100%, so Chart.js fell back to its ~150px default: a squashed
8.6:1 sliver that didn't match the mockups. Set a definite height (420px
desktop, 360px mobile where the chips row sits above the canvas).

Verified on staging by patching the live height: canvas went from
1287x150 to 1287x392 (desktop) / 284 (mobile) — proper ~3:1 proportions
matching the mockup, with the England dashed line, COVID/2021-22 gap and
table all reading correctly.

An e2e guard asserts the trends canvas is taller than 220px so the
squash can't regress.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0146VHeLAWjDVE2B5uU67jCB
---
 e2e/tests/journeys.spec.ts                         |  7 ++++++-
 .../components/compare/TrendsExplorer.module.css   | 14 +++++++++++++-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/e2e/tests/journeys.spec.ts b/e2e/tests/journeys.spec.ts
index 936dfe2..b0a9e96 100644
--- a/e2e/tests/journeys.spec.ts
+++ b/e2e/tests/journeys.spec.ts
@@ -213,7 +213,12 @@ 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 {