diff --git a/app/assets/stylesheets/dialog.css b/app/assets/stylesheets/dialog.css
index 5d6a7eb0e..4e10ccabb 100644
--- a/app/assets/stylesheets/dialog.css
+++ b/app/assets/stylesheets/dialog.css
@@ -35,4 +35,9 @@
       }
     }
   }
+
+  /* Ensure padding from viewport edges */
+  .dialog.panel {
+    max-inline-size: calc(100vw - var(--inline-space-double) * 2);
+  }
 }
diff --git a/app/views/boards/edit/_delete.html.erb b/app/views/boards/edit/_delete.html.erb
index ec346f590..9d9b7f441 100644
--- a/app/views/boards/edit/_delete.html.erb
+++ b/app/views/boards/edit/_delete.html.erb
@@ -3,7 +3,7 @@
     <%= icon_tag "trash" %>
     <span>Delete this board</span>
   </button>
-  <dialog class="dialog panel fill-white shadow gap flex-column" style="max-width: 40ch" data-dialog-target="dialog">
+  <dialog class="dialog panel fill-white shadow gap flex-column" style="--panel-size: 40ch" data-dialog-target="dialog">
     <h3 class="txt-large txt-bold">Delete this board?</h3>
     <p class="txt-medium margin-block-half">Are you sure you want to permanently delete this board and all the cards on it? This can't be undone.</p>
     <div class="flex gap-half justify-center margin-block-start">
diff --git a/app/views/cards/_delete.html.erb b/app/views/cards/_delete.html.erb
index 43afbbad2..e6b999ee0 100644
--- a/app/views/cards/_delete.html.erb
+++ b/app/views/cards/_delete.html.erb
@@ -3,7 +3,7 @@
     <%= icon_tag "trash" %>
     <span>Delete this card</span>
   </button>
-  <dialog class="dialog panel fill-white shadow gap flex-column" style="max-width: 40ch" data-dialog-target="dialog">
+  <dialog class="dialog panel fill-white shadow gap flex-column" style="--panel-size: 40ch" data-dialog-target="dialog">
     <h3 class="txt-large txt-bold">Delete this card?</h3>
     <p class="txt-medium margin-block-half">Are you sure you want to permanently delete this card?</p>
     <div class="flex gap-half justify-center margin-block-start">