Problem Description:

The following custom styling snippet is offered in theory only. You will probably need to adjust this for your own site, and please be aware that it will not translate to mobile views of the site.

Answer:

Custom CSS goes into the Custom CSS box in Theme Options under Custom Styling.

.logo{display: block; float: none; margin: 0px auto; max-width: 320px; margin-bottom: 30px;)

ul#nav{float: none; text-align: center; width: 100%; clear: both; position: inherit;}

ul#nav li{display: inline-block; float: none;}