How to Center My Header

Yikes! I somehow made my center aligned left on my custom theme, and the support of the custom theme company I went through took a look and says that everything in my CSS looks normal- so either a plugin is causing the left alignment or I changed something in my functions file!

Can someone please help me? I am lost on where to go from here. Thanks guys!

https://www.thedriftingdesk.com

I think this might be where I have my header:

.header-image .site-title > a {
background-size: contain !important;
display: block;
height: 164px;
margin: 0 auto;
width: 360px;
text-indent: -9999px;