Purpose of CSS
Separation of semantic and presentational markup
All of this, and more, is possible because the semantic mark-up (such as the HTML or XHTML or XML) is separated from the presentational mark-up (the CSS).
Indeed, this is the purpose of CSS, to allow the separation of the semantic mark-up and the presentational mark-up. This is also the reason why the HTML style tags and attributes have been deprecated, to separate the semantic mark-up from the presentational mark-up.
Vocabulary
- XHTML (and HTML and XML, etc.) is the "semantic mark-up" for the underlying structure of the document.
- CSS is the "presentational mark-up" for the flourish of styles, for the presentation of the document.
It is not enough for us to repeat these technical phrases like parrots could. We must understand the meaning …