[2] [[擬似クラス]]である [DFN[[CODE(CSS)@en[[[:nth-child()]]]]]], [DFN[[CODE(CSS)@en[[[:nth-last-child()]]]]]],
[DFN[[CODE(CSS)@en[[[:nth-of-type()]]]]]], [DFN[[CODE(CSS)@en[[[:nth-last-of-type()]]]]]],
[DFN[[CODE(CSS)@en[[[:first-child]]]]]], [DFN[[CODE(CSS)@en[[[:last-child]]]]]],
[DFN[[CODE(CSS)@en[[[:only-child]]]]]], [DFN[[CODE(CSS)@en[[[:only-of-type]]]]]]
は、[[親要素]]中の[[要素]]の位置によって[[一致]]するものです。

* 仕様書

[REFS[
- [1] [CITE@en[Selectors Level 3]] ([TIME[2011-09-29 22:16:17 +09:00]] 版) <http://www.w3.org/TR/selectors/#structural-pseudos>
]REFS]