Selector

Developing with the SDK > Using CSS Syntax in the Style Sheet > The CSS Syntax > Selector

Selector

The W3C states that "A selector represents a structure. This structure can be understood for instance as a condition that determines which elements in the document tree are matched by this selector, or as a flat description of the HTML or XML fragment corresponding to that structure."

A selector is composed of one or more minimal building blocks. When two or more minimal building blocks are aggregated into a selector, they may be separated by combinators.

A combinator is a single character which semantics is described in Table 3.1. Extra spaces are ignored.

Table 3.1 Combinator Symbols

Transition	Meaning
E F	Matches an F element that is a descendant of an E element
E > F	Matches an F element that is a child of an E element
E + F	Matches an F element immediately preceded by an E element

The minimal building blocks of a selector are listed in Table 3.2. For an explanation of the Specificity column, see Priority.

Table 3.2 Minimal Building Blocks of a Selector

Building Block	Matching Rule	Specificity
e	Matches any element of type e	0-0-1
#myid	Matches any element with an ID equal to myid	1-0-0
.myclass	Matches any element with class myclass	0-1-0
:myclass	Matches any element with pseudo-class myclass	0-1-0
[myattr]	Matches any element with the myattr attribute that exists and <> null	0-1-0
[myattr="warning"]	Matches any element whose myattr attribute value is exactly equal to warning	0-1-0
[myattr~="warning"]	Matches any element whose myattr attribute value is a list of space-separated values, one of which is exactly equal to warning	0-1-0
*	Matches any element	0-0-0

For example, the following line:

P.pastoral.marine { color : green ; size : 10pt ; }

matches <P class="pastoral marine old">, sets the color of the paragraph to green, and sets the font size to 10.

All rules start and end with an implicit " * " pattern. This means that a selector can match anywhere inside the hierarchy.

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