ELIA5 - "Child Theming" with T3 Framework

Hello,

First off let me say this is my first real dive into Joomla development and love the T3 framework. I usually work with Wordpress so this is all very new to me. The major issue I am running into right now is "Child Theming". With Wordpress you can create a theme that links to a parent theme so any changes made to css or core files wont be overwritten with updates. Is this possible with T3? Joomla?

If so how would I go about doing this? Sorry for the very basic question and I hope it has an easy answer.

Thanks very much