Easy-going HTML5

I remember, back in school, every so often our super-mean (but actually very good) math teacher would be away. The class would breathe a collective sigh of relief as, rather than "Mr. Mean" (names have been changed to protect the innocent), the replacement teacher was usually an easy-going and amiable man. He sat quietly and left us to get on without shouting or constant needling. He didn't insist on silence whilst we worked, he didn't much care if we adhered to the way he worked out problems, all that mattered was the answers and that we could articulate how we came to them. If HTML5 were a math teacher, it would be that easy-going supply teacher. I'll now qualify this bizarre analogy.

If you pay attention to how you write code, you'll typically use lower-case for the most part, wrap attribute values in quotation marks, and declare a "type" for scripts and style sheets. For example, perhaps you link to a style sheet like this:

<link href="CSS/main.css" rel="stylesheet...