Thumbnails pushed with Internet Explorer

Hi all,

I've a strange problem with IE7/8 : rolling-over thumbnails images add a sort of with space on each <li></li> element and push back each element (visible here => afairesoimeme.net)

It seems that css code is added to each <li> like above :

<UL id=g-album-grid class=ui-helper-clearfix>
<LI style="POSITION: relative; HEIGHT: 269px; TOP: 0px; LEFT: 0px" id=g-item-id-2 class="g-item g-album" jQuery1333119448843="119">
<DIV style="MARGIN-TOP: etc......</DIV></LI>

Does anyone knows how to modify this css code generated by php ?

Thanks a lot.
Regards