The UIKIT Theme is a generic theme built using the UIKIT Framework. This theme has minimal customizations from the stock UIKIT look and feel. It is designed to be a starting point for sites that wish to create their own unique theme. Although, there is nothing preventing you from using the UIKIT theme as-is for your site.
The UIKIT framework theme is really meant to be a starting point to customize your site. While it can be used as the primary theme for your site, you should consider customizing it for a unique look and feel.
The UIKIT theme expects the main navigation menu to be named navigation in Menu Builder.
The Off-Canvas menu is named navigation_mobile.
Blocks are used in glFusion to deliver specific, small blocks of content in various locations.
The UIKIT Theme utilizes blocks in the right side navigation and in the footer area. In the glFusion Block Administration screen, you can configure which blocks display in each location.
Any overrides to the styles should be done in the theme's custom.css file.
See the wiki section on Customizing the Look and Feel of glFusion for details on how to customize the UIKIT based themes.