The instructions provided were being a bit outdated (as a result of adjustments made to google and payapl sites), but support for this module is superb. CSS is the acronym for "Cascading Model Sheet". It is a style sheet language utilized for describing the presentation of a document published within https://www.presta-addons-modules.com/en/seo/prestashop-gtmetrix-speed-test-api-integration-module.html