See omeka/Omeka#770

There is a 1px border on a.open that makes parent-node navbar items grow when hovered over; that should be removed.

#primary-nav .nav-item > a.open {
    background-color: #fff;
>>>    border: 1px solid #dedede; 
    border-bottom: none;
    z-index: 1;
  }

https://github.com/omeka/theme-santa-fe/blob/master/css/style.css#L884

https://github.com/omeka/theme-santa-fe/blob/master/css/style.css#L1087

There are now header image and accompanying alt text settings available for Santa Fe. Test that the header images appear when uploaded, and look appropriately sized for both desktop and mobile resolutions.

I've also removed Susy, which is a css column layout system that's no longer supported. Look through the theme for any obvious layout oddities, like odd section widths or content sitting where it shouldn't. Exhibit Builder and the item advanced search are areas to look out for.