Youtube has been a prominent long lasting titan in the online entertainment industry, for potentially even longer than I myself have known. Of course, a site as popular as Youtube would be competent users of CSS, and I have chosen it as my website to review.
Youtube's home page design has basically been unchanged for a decade, but it's still incredibly iconic and clean. The display's color is user dependent, allowing for the users to choose between light and dark modes. The thumbnails of each video created by different users are also clearly displayed, aswell as the short preview of the media when hovered over.
I then went and clicked on a piece of media of one of my favorite musical artists, Eminem. The media and audio properly play, and the subscription, like/dislike, share, and more buttons all work properly. On the right is a display of other media, gathered by the algorithm, which can all be clicked. Overall, a simple but extremely effective way to broadcast media to viewers everywhere.
I think the overall design of Youtube is simple, but extremely effective and user friendly, with many quality of life features. Going along with it, the visual design of Youtube is incredibly simple, as it's not trying to catch your eye, the videos are. I'd give the design an 8/10.
The usability of Youtube is frankly amazing, everything works smoothly and does what it is meant to do, mainly because of said simplistic design. You click a video, you're taken to that video. You look something up, the algorithm displays videos based on your search. Even your recent watches will influence what you receive, as the algorithm will recommend videos similar to the ones you've tended to watch over a recent period of time. 10/10 when it comes to usability easily.
Overall, Youtube meets the purpose it was created to make in a simplistic, yet very practical manner. There's a reason why it's stood at the top of the online entertainment industry.