CSS: The bad bits and how to avoid them
There's nothing wrong with styling on an id.You could put the style right in the HTML tag, or on the page where it's used, but with dynamic pages (and static stylesheets) both options will cost you bandwidth.And they split up your styles into separate places.So putting the style on the id is the right thing to do, and I don't understand why the author is against it.If I need my footer to look a certain way, then #footer {} is exactly what you should do.Not add some bogus class based style just in case someone decides we need two footers on one page.