diff --git a/addons/mass_mailing/__manifest__.py b/addons/mass_mailing/__manifest__.py
index aff863f7ab7..42a8ebe3ee5 100644
--- a/addons/mass_mailing/__manifest__.py
+++ b/addons/mass_mailing/__manifest__.py
@@ -116,6 +116,7 @@
             'mass_mailing/static/src/js/snippets.editor.js',
             'mass_mailing/static/src/js/wysiwyg.js',
             'mass_mailing/static/src/xml/mass_mailing.editor.xml',
+            'mass_mailing/static/src/scss/mass_mailing.wysiwyg.scss',
         ],
         'web.assets_common': [
             'mass_mailing/static/src/js/tours/**/*',
diff --git a/addons/mass_mailing/static/src/scss/mass_mailing.ui.scss b/addons/mass_mailing/static/src/scss/mass_mailing.ui.scss
index e1f5f81fe93..cc2ae43b7e9 100644
--- a/addons/mass_mailing/static/src/scss/mass_mailing.ui.scss
+++ b/addons/mass_mailing/static/src/scss/mass_mailing.ui.scss
@@ -344,16 +344,19 @@ body.editor_enable.o_basic_theme.o_in_iframe {
             display: block;
         }
     }
-    #oe_snippets.o_loaded {
-        transform: translateX(0);
+}
 
-        > .o_we_customize_panel .oe-toolbar {
-            #style.dropup, #font-size.dropup {
-                > .dropdown-menu {
-                    overflow-y: scroll;
-                    max-height: 200px;
-                }
+.o_mass_mailing_iframe #oe_snippets.o_loaded {
+    transition: none;
+    transform: translateX(0);
+
+    > .o_we_customize_panel .oe-toolbar {
+        #style.dropup, #font-size.dropup {
+            > .dropdown-menu {
+                overflow-y: scroll;
+                max-height: 200px;
             }
         }
     }
 }
+
diff --git a/addons/mass_mailing/static/src/scss/mass_mailing.wysiwyg.scss b/addons/mass_mailing/static/src/scss/mass_mailing.wysiwyg.scss
new file mode 100644
index 00000000000..abdeb37b90e
--- /dev/null
+++ b/addons/mass_mailing/static/src/scss/mass_mailing.wysiwyg.scss
@@ -0,0 +1,15 @@
+.o_mass_mailing_iframe body {
+    padding-right: $o-we-sidebar-width !important;
+
+    #web_editor-top-edit .note-popover .popover {
+        right: $o-we-sidebar-width !important;
+    }
+
+    .modal:not(.o_technical_modal) {
+        top: 0 !important;
+        // set z-index so customize options visible on dialog.
+        z-index: $o-we-overlay-zindex - 1;
+        // just for fake backdrop effect
+        background-color: rgba(66, 66, 66, 0.4);
+    }
+}
diff --git a/addons/mass_mailing/views/snippets_themes.xml b/addons/mass_mailing/views/snippets_themes.xml
index fffe372b867..839ac65ccd5 100644
--- a/addons/mass_mailing/views/snippets_themes.xml
+++ b/addons/mass_mailing/views/snippets_themes.xml
@@ -23,7 +23,7 @@
     <xpath expr="//t[@id='default_snippets']" position="replace">
         <t id="default_snippets">
             <t t-set="company_id" t-value="res_company"/>
-            <div id="email_designer_themes">
+            <div id="email_designer_themes" class="d-none">
                 <div data-name="basic"
                      title="Plain Text"
                      data-nowrap="1"
diff --git a/addons/web_editor/static/src/scss/wysiwyg_snippets.scss b/addons/web_editor/static/src/scss/wysiwyg_snippets.scss
index 6615db54978..04604956873 100644
--- a/addons/web_editor/static/src/scss/wysiwyg_snippets.scss
+++ b/addons/web_editor/static/src/scss/wysiwyg_snippets.scss
@@ -2,23 +2,6 @@
 /// This file contains all variables and mixins that are specific to the editor.
 ///
 
-// OVERRIDES FOR EDITOR WITH SNIPPETS
-body.editor_enable.editor_has_snippets {
-    padding-right: $o-we-sidebar-width !important;
-
-    #web_editor-top-edit .note-popover .popover {
-        right: $o-we-sidebar-width !important;
-    }
-
-    .modal:not(.o_technical_modal) {
-        top: 0 !important;
-        // set z-index so customize options visible on dialog.
-        z-index: $o-we-overlay-zindex - 1;
-        // just for fake backdrop effect
-        background-color: rgba(66, 66, 66, 0.4);
-    }
-}
-
 // Mobile fix for mass mailing
 @include media-breakpoint-down(lg) {
     body.editor_enable.editor_has_snippets {