Embedded themes does not contain .theme file nor graphic, that is embedded in PeaZip for maximum startup performances.
It is possible to display a custom logo (up to 192 px width, 64 px height) in PeaZip file manager’s toolbar, replacing fm-theme.bmp in theme’s folder with a custom graphic file in BMP format.

Seven theme provides icons meant to integrate the application's look and feel in a Windows 10 or more recent environment, in order to provide more familiar visual metaphors to users of those systems.
Icons are derived from:

Tango Desktop Project

Original reference: http://tango.freedesktop.org/Tango_Desktop_Project
Original license: Attribution-Share Alike 2.5 Generic http://creativecommons.org/licenses/by-sa/2.5/

Crystal and CristalClear

Original reference: http://www.everaldo.com/crystal/
Original license: LGPL

NuoveXT

Original reference: http://nuovext.pwsp.net/
Original license: LGPL