Your Chrome browser has incredibly powerful website development tools built in!
Katrinah shows you (using the Chrome Developer tools) how to adjust the spacing between the social icons in the footer of her YouTube video Sydney: How To Create A WordPress Website 2016 from 1:02:40 to 106:10.
The key to safely and successfully making style changes in your WordPress theme is to make all the changes in a child theme that you create. Katrinah has created a short video that explains what a child theme is and how to create effortlessly using a plugin: How To Create A WordPress Child Theme in 4 Minutes.
For a detailed explanation of what is going on in Katrinah’s video in the above section, please see Using Chrome Developer Tools: Elements (1/6) by codecourse. The video is very clear but it presumes basic knowledge of HTML and CSS.
Codecourse has 5 more videos on Chrome Developer tools which are also very good. But his first video above is all you need to fine tune the elements as Katrinah does in her YouTube video.