Balance-Blue-Dark theme is a combination of the best features of the official Zorin OS themes, along with some minor modifications.

The source code for the original Zorin OS themes can be found at this links:

https://github.com/ZorinOS/zorin-desktop-themes

https://github.com/ZorinOS/zorin-icon-themes

Features of Balance-Blue-Dark:

• Icons are borrowed from ZorinBlue-Light and ZorinGrey-Dark
• GTK 3.0 CSS styling is borrowed from ZorinGrey-Dark theme but I made colors a bit bluish and brighter than the original theme.
• The GNOME shell theme is borrowed from ZorinGrey-Dark theme but I made colors a bit bluish and brighter than the original theme.
• The beautiful blue gradient color used in ZorinBlue-Light is added to this theme.
• Fix some bugs of Zorin original dark themes.

Download and extract this git repository:

wget https://github.com/m3y54m/Balance-Blue-Dark/archive/refs/heads/master.zip
unzip master.zip 
cd Balance-Blue-Dark-master

Copy Balance-Blue-Dark to .themes directory:

mkdir -p ~/.themes
cp -r Balance-Blue-Dark ~/.themes

Copy Balance-Blue-Dark-Icons to .icons directory:

mkdir -p ~/.icons
cp -r Balance-Blue-Dark-Icons ~/.icons

Now you can activate Balance-Blue-Dark theme and Balance-Blue-Dark-Icons icons theme using Zorin Appearance or GNOME Tweaks.