diff --git a/src/__tests__/table-scroll-container-guard.test.ts b/src/__tests__/table-scroll-container-guard.test.ts
new file mode 100644
index 000000000..f5470e2da
--- /dev/null
+++ b/src/__tests__/table-scroll-container-guard.test.ts
@@ -0,0 +1,66 @@
+/**
+ * A sideways-scrolling table wrapper is a positioned box.
+ *
+ * Screen-reader text (`sr-only`) is absolutely positioned. Inside a scroll
+ * container that is not positioned, its containing block is an ancestor
+ * outside the container, so it escapes the container's clipping, and a cell
+ * panned past the phone's edge widens the whole page: the admin login
+ * overview scrolled sideways at 390 px once its IP button gained screen-reader
+ * text. Every `overflow-x-auto` wrapper around a table therefore carries
+ * `relative`, which makes it the containing block of what it scrolls.
+ */
+import { join } from "node:path";
+import { describe, expect, it } from "vitest";
+
+import { readSourceText, walkSourceFiles } from "./helpers/source-files";
+
+const SRC = join(process.cwd(), "src");
+
+/** `file:line` of each table wrapper that scrolls without being positioned. */
+function offenders(rel: string, text: string): string[] {
+  if (!text.includes("<table") || !text.includes("overflow-x-auto")) return [];
+  const lines = text.split("\n");
+  const out: string[] = [];
+  lines.forEach((line, index) => {
+    if (!/"[^"]*\boverflow-x-auto\b[^"]*"/.test(line)) return;
+    if (/^\s*(\*|\/\/)/.test(line)) return;
+    const window = lines.slice(index, index + 8).join("\n");
+    if (window.includes("<table") && !/\brelative\b/.test(line)) {
+      out.push(`${rel}:${index + 1}`);
+    }
+  });
+  return out;
+}
+
+describe("sideways-scrolling table wrappers", () => {
+  const files = walkSourceFiles(SRC, { floor: 1500 }).filter(
+    (rel) =>
+      rel.endsWith(".tsx") &&
+      !rel.includes("__tests__") &&
+      !rel.startsWith("generated/"),
+  );
+
+  it("reads the wrappers it claims to check", () => {
+    const wrappers = files.filter((rel) => {
+      const text = readSourceText(join(SRC, rel));
+      return text.includes("<table") && text.includes("overflow-x-auto");
+    });
+    expect(wrappers.length).toBeGreaterThan(8);
+  });
+
+  it("are positioned, so what they scroll cannot widen the page", () => {
+    const found = files.flatMap((rel) =>
+      offenders(rel, readSourceText(join(SRC, rel))),
+    );
+    expect(found).toEqual([]);
+  });
+
+  it("catches the shape it guards against", () => {
+    const bad = ['<div className="overflow-x-auto">', "  <table>"].join("\n");
+    expect(offenders("x.tsx", bad)).toEqual(["x.tsx:1"]);
+    const good = ['<div className="relative overflow-x-auto">', "<table>"].join(
+      "\n",
+    );
+    expect(offenders("x.tsx", good)).toEqual([]);
+  });
+});
diff --git a/src/components/admin/__tests__/app-log-preview-summary-position.test.tsx b/src/components/admin/__tests__/app-log-preview-summary-position.test.tsx
index 9968dc244..49d9a679f 100644
--- a/src/components/admin/__tests__/app-log-preview-summary-position.test.tsx
+++ b/src/components/admin/__tests__/app-log-preview-summary-position.test.tsx
@@ -83,7 +83,9 @@ describe("AppLogPreviewSection — summary lives outside the scroll wrapper", ()
     const summaryIdx = html.indexOf('data-testid="app-log-preview-summary"');
     expect(summaryIdx).toBeGreaterThan(-1);
     const before = html.slice(0, summaryIdx);
-    const lastScrollOpen = before.lastIndexOf('class="overflow-x-auto"');
+    const lastScrollOpen = before.lastIndexOf(
+      'class="relative overflow-x-auto"',
+    );
     expect(lastScrollOpen).toBeGreaterThan(-1);
     const tail = before.slice(lastScrollOpen);
     expect(tail).toContain("</div>");
@@ -92,7 +94,7 @@ describe("AppLogPreviewSection — summary lives outside the scroll wrapper", ()
   it("does not nest the summary copy inside the scroll wrapper", () => {
     const html = render();
     const wrapper = html.match(
-      /<div class="overflow-x-auto"[^>]*>[\s\S]*?<\/table><\/div>/,
+      /<div class="relative overflow-x-auto"[^>]*>[\s\S]*?<\/table><\/div>/,
     );
     expect(wrapper).not.toBeNull();
     expect(wrapper![0]).not.toContain("app-log-preview-summary");
diff --git a/src/components/admin/__tests__/login-overview-pagination-position.test.tsx b/src/components/admin/__tests__/login-overview-pagination-position.test.tsx
index c37af0740..f1af9b3ac 100644
--- a/src/components/admin/__tests__/login-overview-pagination-position.test.tsx
+++ b/src/components/admin/__tests__/login-overview-pagination-position.test.tsx
@@ -98,7 +98,9 @@ describe("LoginOverviewSection — pagination lives outside the scroll wrapper",
     );
     expect(paginationIdx).toBeGreaterThan(-1);
     const before = html.slice(0, paginationIdx);
-    const lastScrollOpen = before.lastIndexOf('class="overflow-x-auto"');
+    const lastScrollOpen = before.lastIndexOf(
+      'class="relative overflow-x-auto"',
+    );
     expect(lastScrollOpen).toBeGreaterThan(-1);
     // Between the scroll-wrapper opening and the pagination opening
     // there must be at least one `</div>` closing the wrapper.
@@ -114,7 +116,7 @@ describe("LoginOverviewSection — pagination lives outside the scroll wrapper",
     // same depth — naively by grabbing up to `</table></div>`, which
     // matches the structure produced by the current implementation.
     const wrapper = html.match(
-      /<div class="overflow-x-auto"[^>]*>[\s\S]*?<\/table><\/div>/,
+      /<div class="relative overflow-x-auto"[^>]*>[\s\S]*?<\/table><\/div>/,
     );
     expect(wrapper).not.toBeNull();
     expect(wrapper![0]).not.toContain("admin.section.auditLog.next");
diff --git a/src/components/admin/ai-quality-section.tsx b/src/components/admin/ai-quality-section.tsx
index 97ee96201..bbef90f84 100644
--- a/src/components/admin/ai-quality-section.tsx
+++ b/src/components/admin/ai-quality-section.tsx
@@ -117,7 +117,7 @@ export function AiQualitySection() {
           title={t("admin.aiQuality.empty")}
         />
       ) : (
-        <div className="overflow-x-auto">
+        <div className="relative overflow-x-auto">
           <table className="w-full text-sm" data-slot="ai-quality-table">
             <thead>
               <tr className="text-muted-foreground border-border border-b text-left text-xs tracking-wider uppercase">
diff --git a/src/components/admin/api-token-overview-section.tsx b/src/components/admin/api-token-overview-section.tsx
index 4989fcbc4..e0696fa27 100644
--- a/src/components/admin/api-token-overview-section.tsx
+++ b/src/components/admin/api-token-overview-section.tsx
@@ -185,7 +185,7 @@ export function ApiTokenOverviewSection() {
                 inner `overflow-x-auto` is a belt-and-suspenders guard
                 for medium viewports with extra-long permission
                 lists. */}
-            <div className="hidden overflow-x-auto md:block">
+            <div className="relative hidden overflow-x-auto md:block">
               <table className="w-full table-fixed text-sm">
                 <colgroup>
                   <col className="w-[18%]" />
diff --git a/src/components/admin/app-log-preview-section.tsx b/src/components/admin/app-log-preview-section.tsx
index 974d3dfbf..4507f4595 100644
--- a/src/components/admin/app-log-preview-section.tsx
+++ b/src/components/admin/app-log-preview-section.tsx
@@ -279,7 +279,7 @@ export function AppLogPreviewSection() {
         // the table is scrolled horizontally. The refresh control was
         // already in the header above the table wrapper.
         <>
-          <div className="overflow-x-auto">
+          <div className="relative overflow-x-auto">
             <table className="w-full text-sm">
               <thead>
                 <tr className="text-muted-foreground border-b text-xs">
diff --git a/src/components/admin/backups-section.tsx b/src/components/admin/backups-section.tsx
index 2f3ab6759..059bb8242 100644
--- a/src/components/admin/backups-section.tsx
+++ b/src/components/admin/backups-section.tsx
@@ -1286,7 +1286,7 @@ export function BackupsSection() {
           {/* Wide layout: the canonical table. Hidden below `md`, where the
               five columns push Download / Restore off-screen behind a
               horizontal scroll; the card list below takes over there. */}
-          <div className="hidden overflow-x-auto md:block">
+          <div className="relative hidden overflow-x-auto md:block">
             <table className="w-full text-sm">
               <thead>
                 <tr className="text-muted-foreground border-b text-xs">
diff --git a/src/components/admin/coach-feedback-section.tsx b/src/components/admin/coach-feedback-section.tsx
index 09ac117bc..3eb6659bb 100644
--- a/src/components/admin/coach-feedback-section.tsx
+++ b/src/components/admin/coach-feedback-section.tsx
@@ -112,7 +112,7 @@ export function CoachFeedbackSection() {
           title={t("admin.coachFeedback.empty")}
         />
       ) : (
-        <div className="overflow-x-auto">
+        <div className="relative overflow-x-auto">
           <table className="w-full text-sm" data-slot="coach-feedback-table">
             <thead>
               <tr className="text-muted-foreground border-border border-b text-left text-xs tracking-wider uppercase">
diff --git a/src/components/admin/encryption-section.tsx b/src/components/admin/encryption-section.tsx
index 4ba20e22b..bbea2f6f8 100644
--- a/src/components/admin/encryption-section.tsx
+++ b/src/components/admin/encryption-section.tsx
@@ -457,7 +457,7 @@ export function ColumnCoverage({
                sideways, and a keyboard user has to be able to reach it
                (axe scrollable-region-focusable). */
               <div
-                className="overflow-x-auto"
+                className="relative overflow-x-auto"
                 tabIndex={0}
                 role="region"
                 aria-label={t("admin.section.encryption.columnsTitle")}
diff --git a/src/components/admin/login-overview-section.tsx b/src/components/admin/login-overview-section.tsx
index 237f34195..8884584c7 100644
--- a/src/components/admin/login-overview-section.tsx
+++ b/src/components/admin/login-overview-section.tsx
@@ -404,7 +404,7 @@ export function LoginOverviewSection() {
           // back to its starting offset. The CSV-export button was
           // already in the toolbar row above the table wrapper.
           <>
-            <div className="overflow-x-auto">
+            <div className="relative overflow-x-auto">
               <table className="w-full text-sm">
                 <thead>
                   <tr className="text-muted-foreground border-b text-xs">
diff --git a/src/components/admin/user-management-section.tsx b/src/components/admin/user-management-section.tsx
index 5ae5c41fb..325beee72 100644
--- a/src/components/admin/user-management-section.tsx
+++ b/src/components/admin/user-management-section.tsx
@@ -348,7 +348,7 @@ export function UserManagementSection() {
               `md:block hidden` swaps it out for the card-list below at
               `< md`. Hiding the table-only wrapper (instead of just
               the cells) saves DOM weight on mobile too. */}
-            <div className="hidden overflow-x-auto md:block">
+            <div className="relative hidden overflow-x-auto md:block">
               <table className="w-full text-sm">
                 <thead>
                   <tr className="text-muted-foreground border-b text-xs">
diff --git a/src/components/insights/coach-panel/result-table.tsx b/src/components/insights/coach-panel/result-table.tsx
index 812adb1e2..4b00bc70b 100644
--- a/src/components/insights/coach-panel/result-table.tsx
+++ b/src/components/insights/coach-panel/result-table.tsx
@@ -179,7 +179,7 @@ export function CoachResultTable({
         tabIndex={0}
         aria-labelledby={titleId}
         className={cn(
-          "focus-visible:ring-input-focus overflow-x-auto rounded-b-lg outline-none focus-visible:ring-2",
+          "focus-visible:ring-input-focus relative overflow-x-auto rounded-b-lg outline-none focus-visible:ring-2",
           expanded && "max-h-96 overflow-y-auto overscroll-contain",
         )}
       >
diff --git a/src/components/settings/api-section.tsx b/src/components/settings/api-section.tsx
index c3e1e73e9..4279624c7 100644
--- a/src/components/settings/api-section.tsx
+++ b/src/components/settings/api-section.tsx
@@ -352,7 +352,7 @@ function ApiEndpointsCard() {
       />
 
       {/* Desktop table — verbatim layout for md+. */}
-      <div className="border-border hidden overflow-x-auto rounded-lg border md:block">
+      <div className="border-border relative hidden overflow-x-auto rounded-lg border md:block">
         <table className="w-full min-w-[760px] text-xs md:min-w-0">
           <thead>
             <tr className="bg-muted/40 text-muted-foreground border-b">
@@ -514,7 +514,7 @@ function ApiTokensCard() {
                 {t("settings.activeTokensTitle")}
               </p>
               {/* Desktop table — verbatim layout for md+, hidden on phones. */}
-              <div className="border-border hidden overflow-x-auto rounded-lg border md:block">
+              <div className="border-border relative hidden overflow-x-auto rounded-lg border md:block">
                 <table className="w-full min-w-[860px] text-sm md:min-w-0">
                   <thead>
                     <tr className="bg-muted/40 text-muted-foreground border-b text-xs">
@@ -695,7 +695,7 @@ function ApiTokensCard() {
                 {showRevokedTokens && (
                   <>
                     {/* Desktop table — verbatim layout for md+. */}
-                    <div className="border-border hidden overflow-x-auto rounded-lg border md:block">
+                    <div className="border-border relative hidden overflow-x-auto rounded-lg border md:block">
                       <table className="w-full min-w-[760px] text-sm md:min-w-0">
                         <thead>
                           <tr className="bg-muted/40 text-muted-foreground border-b text-xs">