[Plugin: Meks Social Widget] Change social icon style

I’m a new user..

Currently using the Meks Social Widget that came with the theme I bought. The widget works fine but I want to change the style of the icons to be more modern – want to make them smaller and greyed out.

Should I add CSS to style the current widget, or is it better to install a different plugin?

Which is the better option in regards to the page functioning properly, load time etc. ? Running into this issue a lot – should I install plugins or add CSS to customize a theme?

Appreciate your help!