diff --git a/backend/scss/main.scss b/backend/scss/main.scss
index 0469b94..49a7d4f 100644
--- a/backend/scss/main.scss
+++ b/backend/scss/main.scss
@@ -251,10 +251,7 @@ body {
 
             input,
             button {
-                // background-color: rgb(52, 40, 85);
                 border-width: 1px;
-                // border-color: white;
-                // color: white;
             }
         }
 
diff --git a/backend/scss/mixins.scss b/backend/scss/mixins.scss
index 4f429d8..2b6836b 100644
--- a/backend/scss/mixins.scss
+++ b/backend/scss/mixins.scss
@@ -1,3 +1,5 @@
+@use 'constants' as consts;
+
 @mixin markdown {
     h1 {
         font-size: 140%;
@@ -23,4 +25,15 @@
     h6 {
         font-size: 100%;
     }
+}
+
+// Common style for popup box like modal dialog and toast.
+@mixin popup {
+    border: 0.1em solid consts.$color-3;
+    border-radius: 0.5em;
+    background-color: consts.$color-2;
+
+    text-align: center;
+    padding: calc(2 * consts.$margin) calc(2 * consts.$margin);
+    box-shadow: -1px 1px 10px rgba(0, 0, 0, 0.3);
 }
\ No newline at end of file
diff --git a/backend/scss/modal-dialog.scss b/backend/scss/modal-dialog.scss
index f21a3e6..c29dd14 100644
--- a/backend/scss/modal-dialog.scss
+++ b/backend/scss/modal-dialog.scss
@@ -1,19 +1,21 @@
+@use 'mixins';
+@use 'constants' as consts;
+
 #modal-dialog {
-    // visibility: hidden;
-    color: white;
-    width: 800px;
-    margin-left: -400px;
-    background-color: black;
-    text-align: center;
-    border-radius: 2px;
-    padding: 16px; // TODO: 'rem' better?
     position: fixed;
     z-index: 1;
     left: 50%;
-    bottom: 30px;
-    box-shadow: -1px 1px 10px rgba(0, 0, 0, 0.3);
-}
+    width: 50%;
+    transform: translate(-50%, 0%);
 
-#modal-dialog.show {
-    visibility: visible;
+    @include mixins.popup;
+
+    // The inner div will cover the entire dialog and prevent user to
+    // click on it to close the dialog. Thus, The use can click outside
+    // the div and it will be considered as a click on the dialog.
+    padding: 0;
+
+    >div {
+        padding: calc(2 * consts.$margin) calc(2 * consts.$margin);
+    }
 }
\ No newline at end of file
diff --git a/backend/scss/toast.scss b/backend/scss/toast.scss
index 0e1d1a9..9a8a6ed 100644
--- a/backend/scss/toast.scss
+++ b/backend/scss/toast.scss
@@ -1,4 +1,5 @@
 @use 'constants' as consts;
+@use 'mixins';
 
 #toasts {
     position: fixed;
@@ -11,18 +12,11 @@
     flex-direction: column;
 
     .toast {
-        // visibility: hidden;
         display: none;
         width: fit-content;
         align-self: center;
 
-        border: 0.1em solid consts.$color-3;
-        border-radius: 0.5em;
-        background-color: consts.$color-2;
-
-        text-align: center;
-        padding: calc(2 * consts.$margin) calc(2 * consts.$margin);
-        box-shadow: -1px 1px 10px rgba(0, 0, 0, 0.3);
+        @include mixins.popup;
 
         margin: consts.$margin;
 
@@ -36,14 +30,6 @@
     }
 }
 
-// #toast.show {
-//     visibility: visible;
-//     animation:
-//         fadein 0.5s,
-//         fadeout 0.5s 9.5s;
-// animation-iteration-count: 1;
-// }
-
 @keyframes fadein {
     from {
         opacity: 0;
diff --git a/backend/templates/modal_dialog.html b/backend/templates/modal_dialog.html
index 49578a9..d7066f7 100644
--- a/backend/templates/modal_dialog.html
+++ b/backend/templates/modal_dialog.html
@@ -1,6 +1,8 @@
 {# Needed by the frontend modal_dialog module. #}
 <dialog id="modal-dialog">
-    <div class="content"></div>
-    <input type="button" class="ok" value="OK">
-    <input type="button" class="cancel" value="Cancel">
+    <div>
+        <div class="content"></div>
+        <input type="button" class="ok" value="OK">
+        <input type="button" class="cancel" value="Cancel">
+    </div>
 </dialog>
\ No newline at end of file
diff --git a/frontend/src/modal_dialog.rs b/frontend/src/modal_dialog.rs
index 01c499a..b81bed1 100644
--- a/frontend/src/modal_dialog.rs
+++ b/frontend/src/modal_dialog.rs
@@ -1,5 +1,5 @@
 use futures::{future::FutureExt, pin_mut, select};
-use web_sys::{Element, HtmlDialogElement};
+use web_sys::{Element, HtmlDialogElement, Node};
 
 use crate::{
     on_click,
@@ -25,20 +25,17 @@ where
 /// Show a modal dialog with a copy of the given HTML element as content and execute an initilizer
 /// to modify the given content.
 /// Call the given function when OK is pressed.
-pub async fn show_and_initialize_with_ok<T, V, W, U>(
+pub async fn show_and_initialize_with_ok<FInit, TInit, FOk, TOk>(
     element_selector: &str,
-    initializer: T,
-    ok: V,
-) -> Option<W>
+    initializer: FInit,
+    ok: FOk,
+) -> Option<TOk>
 where
-    T: AsyncFn(Element) -> U,
-    V: Fn(Element, U) -> W,
+    FInit: AsyncFn(Element) -> TInit,
+    FOk: Fn(Element, TInit) -> TOk,
 {
     let dialog: HtmlDialogElement = by_id("modal-dialog");
 
-    let input_ok: Element = dialog.selector(".ok");
-    let input_cancel: Element = dialog.selector(".cancel");
-
     let content_element = dialog.selector::<Element>(".content");
 
     let element: Element = selector_and_clone(element_selector);
@@ -46,16 +43,25 @@ where
     content_element.append_child(&element).unwrap();
     let init_result = initializer(element.clone()).await;
 
+    let input_ok: Element = dialog.selector(".ok");
+    let input_cancel: Element = dialog.selector(".cancel");
+
     dialog.show_modal().unwrap();
 
     let click_ok = on_click::OnClick::new(&input_ok).fuse();
     let click_cancel = on_click::OnClick::new(&input_cancel).fuse();
 
-    pin_mut!(click_ok, click_cancel);
+    let dialog_cloned = dialog.clone();
+    let click_dialog =
+        on_click::OnClick::new_with_filter(&dialog, move |node| node == &dialog_cloned as &Node)
+            .fuse();
+
+    pin_mut!(click_ok, click_cancel, click_dialog);
 
     let result = select! {
         () = click_ok => Some(ok(element, init_result)),
         () = click_cancel => None,
+        () = click_dialog => None,
     };
 
     dialog.close();
diff --git a/frontend/src/on_click.rs b/frontend/src/on_click.rs
index 0c2b694..7a63190 100644
--- a/frontend/src/on_click.rs
+++ b/frontend/src/on_click.rs
@@ -7,7 +7,7 @@ use std::{
     task::{Context, Poll},
 };
 use wasm_bindgen::prelude::*;
-use web_sys::EventTarget;
+use web_sys::{EventTarget, Node};
 
 // From: https://docs.rs/gloo-events/latest/gloo_events/struct.EventListener.html
 
@@ -19,11 +19,25 @@ pub struct OnClick {
 
 impl OnClick {
     pub fn new(target: &EventTarget) -> Self {
+        Self::new_with_filter(target, |_| true)
+    }
+
+    pub fn new_with_filter<F>(target: &EventTarget, filter: F) -> Self
+    where
+        F: Fn(&Node) -> bool + 'static,
+    {
         let (sender, receiver) = mpsc::unbounded();
 
-        // Attach an event listener.
-        let listener = EventListener::new(target, "click", move |_event| {
-            sender.unbounded_send(()).unwrap_throw();
+        let listener = EventListener::new(target, "click", move |event| {
+            let mut send = true;
+            if let Some(event_target) = event.target() {
+                if let Some(node) = event_target.dyn_ref::<Node>() {
+                    send = filter(node);
+                }
+            }
+            if send {
+                sender.unbounded_send(()).unwrap_throw();
+            }
         });
 
         Self { receiver, listener }
diff --git a/frontend/src/pages/dev_panel.rs b/frontend/src/pages/dev_panel.rs
index ef42c1e..ac61419 100644
--- a/frontend/src/pages/dev_panel.rs
+++ b/frontend/src/pages/dev_panel.rs
@@ -1,4 +1,4 @@
-use gloo::{events::EventListener, utils::document};
+use gloo::{console::log, events::EventListener, utils::document};
 use wasm_bindgen_futures::spawn_local;
 
 use crate::{
@@ -61,7 +61,11 @@ pub fn setup_page() {
 
     EventListener::new(&by_id("test-modal-dialog"), "click", move |_event| {
         spawn_local(async move {
-            modal_dialog::show("#hidden-templates .modal-test-message").await;
+            if modal_dialog::show("#hidden-templates .modal-test-message").await {
+                log!("Ok");
+            } else {
+                log!("Cancel");
+            }
         });
     })
     .forget();
diff --git a/frontend/src/utils.rs b/frontend/src/utils.rs
index 3856111..3fbb3bf 100644
--- a/frontend/src/utils.rs
+++ b/frontend/src/utils.rs
@@ -49,6 +49,23 @@ impl SelectorExt for Element {
     }
 }
 
+// Not used anymore.
+// pub trait NodeHelperExt {
+//     fn is_parent(&self, child: &Node) -> bool;
+// }
+// impl NodeHelperExt for Node {
+//     fn is_parent(&self, child: &Node) -> bool {
+//         let mut node = child.clone();
+//         while let Some(parent) = node.parent_node() {
+//             if &parent == self {
+//                 return true;
+//             }
+//             node = parent;
+//         }
+//         false
+//     }
+// }
+
 pub fn selector<T>(selectors: &str) -> T
 where
     T: JsCast,