960 grids with taxonomy

Hello,

In the admin/appearance/settings/commerce_kickstart_theme page I can adjust the number of columns for 960 grids for each region.

I've activate the taxonomy/term view and the grid used is like bellow.
I use the teaser mode to display nodes and I don't find where I can adjust the grids.

<div class="views-row">
<article id="node-product-display-28" class="node node-product-display node-teaser contextual-links-region node-product-type node-product-display node-product-type-teaser node-product-display-teaser node-published node-not-promoted node-not-sticky self-posted author-admin-hengel-shop odd clearfix">
<div class="contextual-links-wrapper contextual-links-processed">
<div class="container-24 grid-14 prefix-1 clearfix">
<div class="commerce-product-field commerce-product-field-field-images field-field-images node-28-product-field-images">
<figure class="field field-name-field-images field-type-image field-label-hidden">
<a href="/shop/fr/piece-detachee/charniere/pivot-femelle-charniere.html">
<img src="http://localhost/shop/sites/default/files/styles/medium/public/1214506.jpg?itok=svV_qryd" alt="Pivot femelle (charnière)" title="Pivot femelle (charnière)" width="220" height="147">
</a>
</figure>
</div>
</div>
<div class="container-24 grid-8 prefix-1">
<div class="container-24 grid-24 clearfix">
</article>
</div>
<div class="views-row">...</div>

How to modify the grid ? I'd like to have something like

<div class="container-12 grid-12 clearfix">

Where I can adjust the grid for teaser display ?

Thanks in advance