Selectors

Group of Selectors

elementname-1, elementname-2

h1, p

Basic selectors

Name Pattern Example  
Universal selector * *  
Type selector E p  
Class selector E.classname
.classname		 p.odd
odd		  
ID selector E#idname
#idname		 p#first-paragraph
#first-paragraph		  
Attribute selector E[attr] p[lang] contain attribute
Attribute selector [attr] [lang] contain attribute
Attribute selector [attr=value] [lang="pt-BR"] value is exactly value
Attribute selector [attr~=value] [class~="odd"] value is a whitespace-separated list of words, one of which is exactly value
Attribute selector [attr|=value] [lang|="BR"] value can be exactly value or can begin with value immediately followed by a hyphen
Attribute selector [attr^=value] [lang^="pt"] value value is prefixed (preceded) by value
Attribute selector [attr$=value] [lang$="BR"] value is suffixed (followed) by value
Attribute selector [attr*=value] [class*="odd"] value contains at least one occurrence of value within the string

Combinators

Name Pattern Example
Adjacent sibling combinator A + B h1 + p
General sibling combinator A ~ B h1 ~ p
Child combinator A > B ul > li
Descendant combinator A B ul li

Pseudo-classes

Name Pattern Example
active pseudo-class :active a:active
checked pseudo-class :checked input:checked
focus pseudo-class :focus input:focus
first-child pseudo-class :first-child ul > li:first-child
hover pseudo-class :hover a:hover
last-child pseudo-class :last-child ul > li:last-child
link pseudo-class :link a:link
nth-child pseudo-class :nth-child ul > li:nth-child(2)
nth-of-type pseudo-class :nth-of-type body > p:nth-of-type(1)
visited pseudo-class :visited a:visited

Pseudo-elements

Name Pattern Example
after pseudo-element ::after p::after
before pseudo-element ::before p::before
first-letter pseudo-element ::first-letter p::first-letter
first-line pseudo-element ::first-line p::first-line
selection pseudo-element ::selection p::selection

Fonte: Selectors Level 3 | W3C