last-child not working properly with article

[ezpool]

Why does article behave differently to div where last-child is concernedHTML\[code\]<div class="parent"><div class="example">111</div><div class="example">111</div><div class="example">111</div><div class="example">111</div></div><br><div class="parent2"><article class="example">111</div><article class="example">111</div><article class="example">111</div><article class="example">111</div></div>\[/code\]CSS\[code\].parent .example{ background-color: red;}.parent .example:last-child{background-color: yellow;}.parent2 .example{ background-color: red;}.parent2 .example:last-child{background-color: yellow;}\[/code\]DEMO: http://jsfiddle.net/chLLa/1/