sub-category color

Hello,
I noticed in your plateform that when a sub-catgory is clicked the category and the sub category are colored in blue  in the left side , how can I apply that to my site ?

Hello,

The colored categories and subcategories are marked as "active" in the CatalogController.cs (located in ~/Presentation/Nop.Web/Controllers/) on line 638 in the public ActionResult CategoryNavigation(int currentCategoryId, int currentProductId) method.
The list item of every category that is active has a class "active" (and the others have class "inactive"). On line 1100 of the style.css in ~/Presentation/Nop.Web/Themes/DefaultClean/Content/css/ you should find the style for the activated categories in the category navigation:

.block .list .active > a {
  color: #4ab2f1;
}

Check if you have the "active" class on the active categories in your Category Navigation. If you do, check if you have the styling for it in the style.css.

Hope that information was helpful!

Regards,
Anton