Why does this CSS ID selector include the element type?

Question

in some CSS code I found out this type of selector

div#someid

1. Is this formally correct?

2. If the answer to (1) is YES, what's the need for the div selector before the #someid, shouldn't the id be unique in a valid web page?

Thanks!

Answer 1

1. Yes it's correct.
2. It might be because it makes the selector more specific. The more specific a selector it is the higher priority it is.

Answer 2

It is fine.

• The stylesheet might be reused between pages which have the id on different elements
• The explicit type provides information for the maintainer about the element
• It makes the selector more specific, e.g. to override #other div.