The site that I found was in the Mozilla Developer website, and the URL would be
Progressive enhancemetns are philosophys in design that can provide functionality and usability. Meaning that a web developer should make websites that are simple, but easy to use websites for all older and newer devices/browsers.
Progressive enchancements are needed because it gives web developers a proper focus on creating the best possible websites while making those sites, work across multiple unknown users and browsers.
This particular website does not validate with both the HTML checker and the W3C CSS validation service.
I found and clicked another link that led me to another page that did not validate. Many of the same errors and warnings.
Throughout the whole two pages that I have validated, there were a total of 44 errors on the HTML checker and 8 errors and 626 warnings on the second page that was validated. On the first page that was validated, there was 43 errors on the HTML checker and 8 errors and 626 warnings.
I would rate the design of this site a solid 6. I thought that the page was fairly plain and boring to look at and read through.
I would rate the sites usability an 8. I thought that this sites usability as great. Everything was easy to find and everything worked correctly.
I think that this site does meet its purpose of providing a resource or multiple resources for many learning developers out there in the world.