NOTE: Test needs to be performed on `advanced` theme.
# enable mod-rewrite
# comment-out `page_title` block definition in `error_notfound.tpl`
# type any non-existing page url in the browser and press ENTER
# confirm, that:
* the `404 Not Found` page is displayed
* browser tab title ends up with `:: Page Not Found`
# disable mod-rewrite
# create a product in Admin Console
# on the Front-End open that product detail page
# in url change id of product to some other number, that doesn't match to any existing product id
# confirm, that:
* the `404 Not Found` page is displayed
* browser tab title ends up with `:: Page Not Found` (before it ended with `::` because `page_title` block from product detail page was used)