fix text color of modal headers in christmas theme

src/client/styles/scss/theme/christmas.scss

@@ -161,9 +161,22 @@ html[dark] {
   /*
   * Modal
   */
-  .modal-dialog .modal-header.bg-primary {
-    background-image: url('/images/themes/christmas/christmas-navbar.jpg');
-    border-bottom: 2px solid $subthemecolor;
+  .modal {
+    .modal-dialog .modal-header.bg-primary {
+      background-image: url('/images/themes/christmas/christmas-navbar.jpg');
+      border-bottom: 2px solid $subthemecolor;
+    }
+
+    .modal-dialog:not(.grw-page-accessories-modal) {
+      .modal-header {
+        .modal-title {
+          color: $themelight;
+        }
+        .close {
+          color: $themelight;
+        }
+      }
+    }
   }
 
   /*