i wish to thank all for helping me , but i believe my issue wasn't well pointed
i believe after deep serch i could solve my problem
with this
https://github.com/yui/yui3/wiki/Understanding-Skinning
PHP Code:
<div class="yui-skin-sam">
<div id="details" class="yui-navset">
<ul class="yui-nav">
so please be kind and tell me how to modify :) thank you