In openerp 7 I have some columns I want to style (set max width). So I have followed the instructions at https://www.odoo.com/forum/help-1/question/changing-column-widths-tree-view-35981, which recommend the following:

xml : <tree string="Tree String" version="7.0" class="my_class"> <field name="my_field" />

css : .my_class [data-id="my_field"]{width: 1000px;}

I have done so, and added the following style for testing:

.x-portal [data-id="name"]{
    width: 10px;
    color: blue;
}

While I can see that the table has been assigned the x-portal class, inspect element reveals that it does not recognize that style, and has not added to the element. I see it pulling all the other appropriate styles from base.css, but not mine. How can I make openerp recognize the css I placed in base.css, or where should I place css so that it will be called without me making a custom module just for this purpose?