Featured Products col width

[Shop Suey]

Hello,
I try to display 3 featured products in a row.
Instead of modifying .CenteredContent I added a new class .33-prozent

.33-prozent{width:33%!important;}

and modified modules/featured_products.php

$list_box_contents[$row][$col] = array('params' =>'class="centerBoxContentsFeatured centeredContent back"' . ' ' . 'style="width:' . $col_width . '%;"',

$list_box_contents[$row][$col] = array('params' =>'class="centerBoxContentsFeatured centeredContent back 33-prozent"' . ' ' . 'style="width:' . $col_width . '%;"',

In chrome inspector the class is being displayed at the "Elements" view but not at the "Styles" view.
Or is another approach better for this?

[Shop Suey]

I managed it via .centerBoxContentsFeatured{width:33%!important;} meanwhile.
Nevertheless I don't understand why the first approach didn't work.