This tutorial goes over how to change the class that is on the custom logo.
Once you have added custom logo support to your WordPress theme you might want to style it. By default, WordPress adds a class called
custom-logo-link when you upload a logo from the WordPress customizer. Since I am using the Bootstrap framework, I wanted to change this class to something Bootstrap already styled out-of-box.
Not only does this save time, but I didn’t have to duplicate styles in my CSS stylesheets.
Below is the WordPress filter used to change the custom logo class in this tutorial.