[FIX] web_editor: restore background and foreground color previews

closes odoo/odoo#58733

X-original-commit: ee8cd9952736d9ea57609e218e3479963785a78d
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/web_editor/static/src/scss/wysiwyg.scss

@@ -78,11 +78,23 @@ $o-we-zindex: $o-we-overlay-zindex + 1 !default;
         background: $o-we-sidebar-content-field-clickable-bg;
         color: inherit;
         font-size: $o-we-font-size !important;
+        border-bottom-color: transparent; // See caret design below
 
         &.active,
         &:focus, &:active, &:focus:active {
             @extend %we-active-button;
         }
+
+        // This element should have been removed but still exists in 13.0 by
+        // mistake. This takes advantage of it to restore the color preview
+        // feature which disappeared and cannot be fixed as in 12.0.
+        // TODO fix the right way in 14.0.
+        > .caret {
+            display: block;
+            @include o-position-absolute(auto, 0, 0, 0);
+            border-bottom: 3px solid transparent;
+            border-bottom-color: inherit;
+        }
     }
     .btn-group.show {
         > .btn {