How to change the number of items per row in products grid?

[Whaaaaat]

How to modify magento 2 to show 3 items per row in product grid instead of the default 4? I tried to play with /var/www/magento2/vendor/magento/theme-frontend-luma/Magento_Catalog/web/css/source/module/_listings.less but nothing changed. I've restarted apahce2... I have flushed magento2 cache ... I have deleted all folders under /magento2/var/cache ... but still showing 4 items per row!!!

 Any suggestions?!

[Magikvishal]

Hi,

Please run below commnd

bin/magento dev:source-theme:deploy

[Whaaaaat]

I've tried ... nothing changed.

Would you please send me the exact detailed steps how to change the number of items per row? maybe I missed one step!