Here's some code that I a short while ago wrote. I imagine that it provides a standard explanation of combining class/ID names with pseudoclasses. The module helps you to incorporate image on all website pages a preloader, also recognised, as being a loading page, or preloading screen it’s the loading https://www.presta-addons-modules.com/en/front-office/prestashop-seo-webmaster-site-verification-for-search-engines.html