diff --git a/TODO.md b/TODO.md
index eddcc3a..4bf1256 100644
--- a/TODO.md
+++ b/TODO.md
@@ -45,6 +45,16 @@ but the review is broader than any of them.
 
 # Completed Steps
 
+- 2026-10-04: The error container on each dApp approval screen keeps its height
+  when an error appears
+  ([#297](https://git.eeqj.de/sneak/AutistMask/issues/297)). `#approve-tx-error`
+  and `#approve-sign-error` reserved 20px, but their border and padding took
+  10px of it, so a one-line error grew them to 26px and pushed the buttons below
+  down 6px. They now reserve 30px. A new test in `tests/e2e/run.js` shows each
+  of the six password error containers on its own screen, empty and then with an
+  error, and fails if one changes height or the element below it moves. Some of
+  the longer messages these two containers can show still take two lines.
+
 - 2026-10-04: A transaction with no `to` says "This transaction creates a new
   contract. It has no recipient." on its recipient line and in its transaction
   history row ([#250](https://git.eeqj.de/sneak/AutistMask/issues/250)). The
diff --git a/src/popup/index.html b/src/popup/index.html
index 741bc1f..554f6be 100644
--- a/src/popup/index.html
+++ b/src/popup/index.html
@@ -1633,7 +1633,7 @@
                 </div>
                 <div
                     id="approve-tx-error"
-                    class="text-xs mb-2 border border-border border-dashed p-1 min-h-[1.25rem]"
+                    class="text-xs mb-2 border border-border border-dashed p-1 min-h-[1.875rem]"
                     style="visibility: hidden"
                 ></div>
                 <div class="flex justify-between">
@@ -1710,7 +1710,7 @@
                 </div>
                 <div
                     id="approve-sign-error"
-                    class="text-xs mb-2 border border-border border-dashed p-1 min-h-[1.25rem]"
+                    class="text-xs mb-2 border border-border border-dashed p-1 min-h-[1.875rem]"
                     style="visibility: hidden"
                 ></div>
                 <div class="flex justify-between">
diff --git a/tests/e2e/run.js b/tests/e2e/run.js
index c3b61de..1a256c1 100644
--- a/tests/e2e/run.js
+++ b/tests/e2e/run.js
@@ -1449,6 +1449,81 @@ test("an over-long flash message keeps to one line (#252)", async (env) => {
     }
 });
 
+// --------------------------------------- password error containers (#297)
+
+// Every screen that asks for a password reserves room for one line of error.
+// The two on the dApp approval screens also have a border and padding, which
+// that reserved height has to cover too.
+const PASSWORD_ERROR_CONTAINERS = [
+    "approve-tx-error",
+    "approve-sign-error",
+    "export-privkey-flash",
+    "show-phrase-flash",
+    "delete-wallet-flash",
+    "confirm-tx-password-error",
+];
+
+// Shows only the screen holding the container, then measures the container
+// and the element below it empty and again filled the way showError() in
+// src/popup/views/helpers.js fills it. Runs in the page.
+function measurePasswordError(id) {
+    const container = document.getElementById(id);
+    const screen = container.closest(".view");
+    for (const view of document.querySelectorAll(".view")) {
+        view.classList.toggle("hidden", view !== screen);
+    }
+    const below = container.nextElementSibling;
+    const measure = () => ({
+        height: container.getBoundingClientRect().height,
+        belowTop: below.getBoundingClientRect().top + window.scrollY,
+        belowHeight: below.getBoundingClientRect().height,
+    });
+    const empty = measure();
+    container.textContent = "Please enter your password.";
+    container.style.visibility = "visible";
+    const filled = measure();
+    container.textContent = "";
+    container.style.visibility = "hidden";
+    return { empty, filled };
+}
+
+test("a password error moves nothing on any screen (#297)", async (env) => {
+    const page = await openPopup(env.ctx, env.popupUrl);
+    try {
+        await page.setViewportSize(POPUP_VIEWPORT);
+        for (const id of PASSWORD_ERROR_CONTAINERS) {
+            const { empty, filled } = await page.evaluate(
+                measurePasswordError,
+                id,
+            );
+            assert(
+                empty.belowHeight > 0,
+                "nothing is shown below #" + id + ", so nothing was measured",
+            );
+            assert(
+                filled.height === empty.height,
+                "#" +
+                    id +
+                    " is " +
+                    empty.height +
+                    "px empty and " +
+                    filled.height +
+                    "px with an error",
+            );
+            assert(
+                filled.belowTop === empty.belowTop,
+                "the element below #" +
+                    id +
+                    " moved " +
+                    (filled.belowTop - empty.belowTop) +
+                    "px when the error appeared",
+            );
+        }
+    } finally {
+        await page.close();
+    }
+});
+
 // --------------------------------------------- confirmation screen (#238)
 //
 // The screen that decides what gets signed. The arithmetic underneath it