Make social media icons round not square in footer

Hi – I have added social media icons to my footer using CSS and this code found on the support page:

<ul class=”noLightbox social_bookmarks icon_count_4″><li class=”social_bookmarks_facebook av-social-link-facebook social_icon_1″><span class=”avia_hidden_link_text”>Facebook</span><li class=”social_bookmarks_twitter av-social-link-linkedin social_icon_2″><span class=”avia_hidden_link_text”>Linkedin</span><li class=”social_bookmarks_mail av-social-link-mail social_icon_4″><span class=”avia_hidden_link_text”>Mail</span>

My question is how do I make these icons round so they appear just like the ones in the header? My site URL is below.

Thank you!
Anna