diff --git a/toolkit/components/prompts/content/commonDialog.css b/toolkit/components/prompts/content/commonDialog.css
index d811fb62d502cf6fc0bf8163f11e1d264dee9e82..9aa4dc90c73e2f1e2fdcb6bdc26a505402a5c28f 100644
--- a/toolkit/components/prompts/content/commonDialog.css
+++ b/toolkit/components/prompts/content/commonDialog.css
@@ -3,7 +3,8 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 :root {
-  min-width: 29em;
+  min-width: 32em;
+  min-height: 12rem;
 }
 
 dialog[insecureauth] {
@@ -91,7 +92,7 @@ dialog[insecureauth] {
     --grid-padding: 16px;
     /* All the inner items should have 4px inline margin, leading to 1.16em spacing
      * between the dialog and its contents, and 8px horizontal spacing between items. */
-    padding: var(--grid-padding) calc(var(--grid-padding) - 4px);
+    padding: 26px 22px;
 
     &::part(dialog-button) {
       /* Adjust vertical margins for buttons in subdialogs. */
