Display product list like Accessories or Best Products for instance

[wbbz]

Hello,

I've started to modify product-list.tpl (the part with class right_block doesn't contain anything now for example) and a little global.css, and have the result you see on the picture.

How can I simply reduce the width of the "frames" containing each product, et have 3 or 4 products displayed on each row?
Like for the best products module (which only appears on the homepage if activated) or the accessories module/tab.

Thanks in advance
Prestashop 1.3.7