Some of these examples are valid and should be common knowledge for all web developers (e.g.: treating CSS semicolons as terminators rather than separators; transitions; unitless values; all [+1]), and some of these examples are a bit questionable. The code style seems a bit esoteric, especially some of the ES. Also, not many of these examples would pass an HTML validator without warnings due to the lack of quotes surrounding attributes. Just a caveat..
Comments
Some of these examples are valid and should be common knowledge for all web developers (e.g.: treating CSS semicolons as terminators rather than separators; transitions; unitless values; all [+1]), and some of these examples are a bit questionable. The code style seems a bit esoteric, especially some of the ES. Also, not many of these examples would pass an HTML validator without warnings due to the lack of quotes surrounding attributes. Just a caveat..
You're wrong, the HTML is valid.