Could you please give a try with the new version 1.0.2 ? https://joomlead.com/joomla-template/green-nature/
You can download the newest version and re-install it or you can download and extract the package then following:
scss folder and replace your current scss folder
+ Copy theme_root/gantry/theme.yaml and replace the existing file.
Note: After installing/adding the new update, please select the base outline mode -> choose an existing preset and then save the style. See https://imgur.com/ZDayiuc
The new Gantry5 5.5 added new scss compiler version, we are working to fix the scss issue with our themes.