CSS From the Ground Up - 4
In trying to keep these tutorials as simple as possible, I have left out some more complicated aspects which are not key to learning the principles – but can't be ignored.
Without going too deeply into the inner workings, I'm going to explain how to make sure that you and the browsers are talking the same language. That means putting a line of text at the top of your Web page markup called a 'DocType' – the type of document it is. Yes, it's a Web page, we all know that, but the browser wants to know the finer details so that it can render it correctly.
Then, something else that might at first seem strange but will soon make sense. That is, taking your Cascading Style Sheet definitions out of your Web page markup completely and putting them in a separate 'external' file so that they can be shared across multiple pages.
Although I've previously dismissed the use of tables for layouts, they still have their uses and, like everything else on a Web page they can be styled to your taste. If you need to present tabular data, it doesn't have to look like a naked spreadsheet!