[HELP] Sociallyviral pro thumbnail grid size

How to change the grid size on homepage, categories, related posts and sidebar. i don't know which is which. here is the FULL style.css

Code:
/*
Theme Name: SociallyViral Pro by MyThemeShop
Theme URI: http://mythemeshop.com/themes/sociallyviral/
Author: MyThemeShop
Author URI: http://mythemeshop.com/
Description: SociallyViral is an engaging WordPress theme that is designed to help boost social shares and get you more viral traffic from the web's top social media websites.
Version: 2.1.13...

[HELP] Sociallyviral pro thumbnail grid size