diff --git a/src/pages/Vortexopedia.tsx b/src/pages/Vortexopedia.tsx
index 2f3ef70..3ae2708 100644
--- a/src/pages/Vortexopedia.tsx
+++ b/src/pages/Vortexopedia.tsx
@@ -124,7 +124,8 @@ const Vortexopedia: React.FC = () => {
                 type="button"
                 size="content"
                 variant="bare"
-                className="w-full text-left"
+                className="block w-full text-left"
+                aria-expanded={expandedId === item.id}
                 onClick={() => toggleExpand(item.id)}
               >
                 <CardHeader className="pb-2">
diff --git a/tests/e2e/vortexopedia.spec.ts b/tests/e2e/vortexopedia.spec.ts
new file mode 100644
index 0000000..d351484
--- /dev/null
+++ b/tests/e2e/vortexopedia.spec.ts
@@ -0,0 +1,49 @@
+import { expect, test } from "@playwright/test";
+
+for (const width of [390, 768, 1024, 1440]) {
+  test(`Vortexopedia entries keep a shared left edge at ${width}px`, async ({
+    page,
+  }) => {
+    await page.setViewportSize({ width, height: 900 });
+    await page.goto("/app/vortexopedia");
+    const entries = page.locator("[data-term-id]");
+    await expect(entries.first()).toBeVisible();
+
+    const offsets = await entries.evaluateAll((cards) =>
+      cards.map((card) => {
+        const button = card.querySelector("button")!;
+        const header = button.firstElementChild!;
+        const bounds = button.getBoundingClientRect();
+        const content = header.getBoundingClientRect();
+        return {
+          left: Math.abs(content.left - bounds.left),
+          right: Math.abs(content.right - bounds.right),
+        };
+      }),
+    );
+    for (const offset of offsets) {
+      expect(offset.left).toBeLessThan(1);
+      expect(offset.right).toBeLessThan(1);
+    }
+
+    const entry = entries.first();
+    const trigger = entry.getByRole("button");
+    const titleBefore = await entry.getByRole("heading").boundingBox();
+    await trigger.click();
+    await expect(trigger).toHaveAttribute("aria-expanded", "true");
+    const details = entry.getByText("Details", { exact: true });
+    await expect(details).toBeVisible();
+    const titleAfter = await entry.getByRole("heading").boundingBox();
+    const detailBounds = await details.boundingBox();
+    expect(titleAfter!.x).toBeCloseTo(titleBefore!.x, 0);
+    expect(titleAfter!.x).toBeCloseTo(detailBounds!.x, 0);
+    expect(
+      await page.evaluate(
+        () => document.documentElement.scrollWidth > window.innerWidth,
+      ),
+    ).toBe(false);
+    await trigger.press("Enter");
+    await expect(trigger).toHaveAttribute("aria-expanded", "false");
+    await expect(details).toBeHidden();
+  });
+}