[FIX] website: restore mobile preview header colors

Part of https://github.com/odoo/odoo/pull/31117
task-1941156

closes odoo/odoo#31117

addons/website/static/src/scss/website.ui.scss

@@ -134,10 +134,14 @@ body .modal {
                     cursor: pointer;
                     font-family: $o-we-font-family;
 
+                    &, .close {
+                        color: white;
+                    }
+
                     h4 {
-                        color: lightgray;
-                        font-family:inherit;
+                        font-family: inherit;
                         font-weight: normal;
+                        color: inherit;
 
                         .fa {
                             margin-left: $grid-gutter-width/2;