diff --git a/toolkit/components/prompts/content/commonDialog.css b/toolkit/components/prompts/content/commonDialog.css
index d811fb62d502cf6fc0bf8163f11e1d264dee9e82..9fd96c560342b3417299ee3c6afda30ddcec76c0 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] {
@@ -91,11 +92,12 @@ 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: 30px 26px;
+    gap: 6px;
 
     &::part(dialog-button) {
       /* Adjust vertical margins for buttons in subdialogs. */
-      margin: 0 4px;
+      margin: 4px 6px 0 6px;
       min-width: auto;
     }
   }
