diff --git a/apps/web/e2e/trace.spec.ts b/apps/web/e2e/trace.spec.ts
index 97a7e85..fd177e3 100644
--- a/apps/web/e2e/trace.spec.ts
+++ b/apps/web/e2e/trace.spec.ts
@@ -42,6 +42,14 @@ test('the trace pane shows machine state at the cursor (X5)', async ({ page }) =
   await expect(facts).toContainText('#6');
   const stackHeading = await page.locator('[data-testid="trace-stack"] h3').textContent();
   expect(stackHeading).toMatch(/Stack \([1-9]\d*\)/);
+
+  // Regression: a full 32-byte word must stay inside its own pane, never
+  // bleeding into Memory or Calldata beside it (missing `.ss-trace-panes`
+  // selector scoping once let long hex words render unclipped).
+  const stackPane = page.locator('[data-testid="trace-stack"]');
+  const paneRight = (await stackPane.boundingBox())!.x + (await stackPane.boundingBox())!.width;
+  const wordBox = await stackPane.locator('li code').first().boundingBox();
+  expect(wordBox!.x + wordBox!.width).toBeLessThanOrEqual(paneRight + 1);
 });
 
 test('step modes navigate the timeline by keyboard (X6)', async ({ page }) => {
diff --git a/apps/web/src/app/app.css b/apps/web/src/app/app.css
index d9fda61..f6bc893 100644
--- a/apps/web/src/app/app.css
+++ b/apps/web/src/app/app.css
@@ -1463,13 +1463,6 @@ input[readonly] {
 }
 
 /* ===== Trace inspector ===== */
-.ss-trace {
-  border: var(--ss-border);
-  border-radius: var(--ss-radius);
-  padding: var(--ss-space-2);
-  margin-top: var(--ss-space-2);
-}
-
 .ss-trace-scrub {
   display: flex;
   align-items: center;
@@ -1490,7 +1483,7 @@ input[readonly] {
   margin-top: var(--ss-space-2);
 }
 
-.ss-trace h3 {
+.ss-trace-panes h3 {
   font-family: var(--ss-font-ui);
   font-size: 0.72rem;
   letter-spacing: var(--ss-tracking-label);
@@ -1499,7 +1492,7 @@ input[readonly] {
   margin: var(--ss-space-2) 0 var(--ss-space-1);
 }
 
-.ss-trace ol {
+.ss-trace-panes ol {
   list-style: none;
   margin: 0;
   padding: 0;
@@ -1510,14 +1503,14 @@ input[readonly] {
   border: var(--ss-border);
 }
 
-.ss-trace li {
+.ss-trace-panes li {
   display: flex;
   gap: var(--ss-space-2);
   padding: 1px var(--ss-space-1);
   overflow: hidden;
 }
 
-.ss-trace li code {
+.ss-trace-panes li code {
   overflow: hidden;
   text-overflow: ellipsis;
   white-space: nowrap;