diff --git a/addons/web_editor/static/src/scss/bootstrap_overridden.scss b/addons/web_editor/static/src/scss/bootstrap_overridden.scss
index f48d9bdaecb..6945a73299e 100644
--- a/addons/web_editor/static/src/scss/bootstrap_overridden.scss
+++ b/addons/web_editor/static/src/scss/bootstrap_overridden.scss
@@ -8,15 +8,17 @@ $colors: () !default;
 }
 
 $o-btn-bg-colors: () !default;
-$o-btn-bg-colors: map-merge((
-    'primary': o-color('o-cc1-btn-primary'),
-    'secondary': o-color('o-cc1-btn-secondary'),
-), $o-btn-bg-colors);
 $o-btn-border-colors: () !default;
-$o-btn-border-colors: map-merge((
-    'primary': o-color('o-cc1-btn-primary-border'),
-    'secondary': o-color('o-cc1-btn-secondary-border'),
-), $o-btn-border-colors);
+@if not (variable-exists('prevent-backend-colors-alteration') and $prevent-backend-colors-alteration) {
+    $o-btn-bg-colors: map-merge((
+        'primary': o-color('o-cc1-btn-primary'),
+        'secondary': o-color('o-cc1-btn-secondary'),
+    ), $o-btn-bg-colors);
+    $o-btn-border-colors: map-merge((
+        'primary': o-color('o-cc1-btn-primary-border'),
+        'secondary': o-color('o-cc1-btn-secondary-border'),
+    ), $o-btn-border-colors);
+}
 
 // Automatically extend bootstrap to create theme background/text/button classes
 $theme-colors: () !default;
@@ -31,6 +33,13 @@ $grays: () !default;
     $grays: map-merge(('#{$name}': o-color($color)), $grays);
 }
 
+// Detach colors that are used for backend UI (see comment linked to the
+// prevent-backend-colors-alteration for more information)
+@if variable-exists('prevent-backend-colors-alteration') and $prevent-backend-colors-alteration {
+    $theme-colors: map-remove($theme-colors, 'primary', 'secondary', 'success', 'info', 'warning', 'danger', 'light', 'dark');
+    $grays: map-remove($grays, '100', '200', '300', '400', '500', '600', '700', '800', '900');
+}
+
 // Bootstrap use standard variables to define individual colors which are then
 // placed into a map which is then used to get the value of each individual
 // color. As BS4 allows to extend the map a priori to define our own colors,
diff --git a/addons/web_editor/static/src/scss/bootstrap_overridden_backend.scss b/addons/web_editor/static/src/scss/bootstrap_overridden_backend.scss
index ef2d6cf03c5..335e8ffd13d 100644
--- a/addons/web_editor/static/src/scss/bootstrap_overridden_backend.scss
+++ b/addons/web_editor/static/src/scss/bootstrap_overridden_backend.scss
@@ -1,14 +1,15 @@
-
-$o-theme-color-palette: map-remove($o-theme-color-palette, 'primary', 'secondary', 'success', 'info', 'warning', 'danger', 'light', 'dark');
-$o-gray-color-palette: map-remove($o-gray-color-palette, '100', '200', '300', '400', '500', '600', '700', '800', '900');
-
-$o-btn-bg-colors: () !default;
-$o-btn-bg-colors: map-merge((
-    'primary': null,
-    'secondary': null,
-), $o-btn-bg-colors);
-$o-btn-border-colors: () !default;
-$o-btn-border-colors: map-merge((
-    'primary': null,
-    'secondary': null,
-), $o-btn-border-colors);
+// TODO the code linked to this variable should not be needed, this needs a lot
+// of refactoring. Basically, "frontend" color (complex) maps are available
+// in all assets (via the variables parts that all assets have in common). The
+// original plan was for them to be used in shared "frontend" environment like
+// the mass_mailing application. The web_editor SCSS generation uses those
+// variables to customize bootstrap variables... but it conflicts with the
+// backend also customizing those. In master it should be reviewed so that the
+// web_editor probably does not touch any bootstrap variable when in a backend
+// environment and/or some code should simply be moved to the website app only.
+// In stable, this next code was made to "clean" what the web_editor alters when
+// in a backend environment.
+// See also web_editor.common.scss where many CSS rules depends on this and are
+// available in the backend... while they probably should not. But in stable,
+// we wanted to avoid changing too many things.
+$prevent-backend-colors-alteration: true;
diff --git a/addons/web_editor/static/src/scss/web_editor.common.scss b/addons/web_editor/static/src/scss/web_editor.common.scss
index f9300b326b3..d292b94a1a2 100644
--- a/addons/web_editor/static/src/scss/web_editor.common.scss
+++ b/addons/web_editor/static/src/scss/web_editor.common.scss
@@ -1,5 +1,9 @@
 ///
-/// This file regroups basic style rules for web_editor enable page edition and backend utils.
+/// This file regroups basic style rules for web_editor enable page edition and
+/// backend utils.
+/// TODO many of those rules should probably not be declared for the backend.
+/// in particular the o_ccX rules, see code linked to the variable named
+/// 'prevent-backend-colors-alteration'.
 ///
 
 :root {