CSS changes

Is there a particular means I need to follow to edit CSS? I’ve tried editing the plugin CSS, theme CSS, adding widget classes. Nothing seems to take.

http://www.ruthmalkinlerner.com/

An example would be .advs-title no matter what I try it keeps getting trumped by .featured-top h2 and/or element.style

I just need to lessen title margin, padding, line-height so there’s not so much space between title and excerpt.

https://wordpress.org/plugins/advanced-post-slider/