Install Templates
Since NagVis 1.1x you can add templates for the header- and hover-menu.
Unpack Template
Unpack the NagVis template in a path of your choice
tar xvzf NagVis-Template--.x.tar.gz
Install NagVis-Template
Place the NagVis-Template directory tree into your NagVis Folder (default /usr/local/nagios/share/nagvis).
cp -r nagvis /usr/local/nagios/share/nagvis
Configure
Open with the WUI "NagVis configuration", select for hover- and headertemplate "darkglass" and save the configuration.
Ready! Now can use NagVis with the new template design.