Over the last year, only ~70% of the visiting browsers supported the new CSS features. Even thought this feature is “widely supported” in a general audience, for my audience, it left out 30% of the visitors.

That mirrors my experience using web pages to order things. They work ~70% of the time. Often while I sit there repeatedly pressing a 'buy' button that does nothing, or playing around with my browser's development tools to try and fix it client side, I wonder how often physical stores cash registers fail, in comparison. Just yesterday I tried to order from a site called buttonworks.com, but the order page only worked in Firefox, and the account/payment pages only worked in Chrome, and I gave up on trying to copy cookies from one browser to another and went with purebuttons.com.