Change facebook icon on hover

Hi,
I’d like to see the facebook logo in the top right corner in my homepage always with the same colours.

<li class=”social_bookmarks_facebook av-social-link-facebook social_icon_1″><span class=”avia_hidden_link_text”>Facebook</span>

<span class=”avia_hidden_link_text”>Facebook</span>

How can I edit custom.css to see the logo always in the same way (hover status have to be the same of the not hover status).

thanks in advance