universal selector

The universal selector, written as a CSS qualified name CSS3NAMESPACE with an asterisk (* U+002A) as the local name, represents the qualified name of any element type. It represents any single element in the document tree in any namespace (including those without a namespace) if no default namespace has been specified for selectors. If a default namespace has been specified, see Universal selector and Namespaces below.

If a universal selector represented by * (i.e. without a namespace prefix) is not the only component of a sequence of simple selectors selectors or is immediately followed by a pseudo-element, then the * may be omitted and the universal selector’s presence implied.

Examples:

*[hreflang|=en] and [hreflang|=en] are equivalent,

*.warning and .warning are equivalent,

*#myid and #myid are equivalent.

Note: it is recommended that the * not be omitted, because it decreases the potential confusion between, for example, div :first-child and div:first-child. Here, div *:first-child is more readable.

Universal selector and namespaces

The universal selector allows an optional namespace component. It is used as follows:

ns|* all elements in namespace ns

*|* all elements

|* all elements without a namespace

* if no default namespace has been specified, this is equivalent to *|*. Otherwise it is equivalent to ns|* where ns is the default namespace.

A universal selector containing a namespace prefix that has not been previously declared is an invalid selector.