xampp/htdocs/zero-one/assets/app/(or wherever Zero One theme files are) and run your terminal. Or run your terminal and go to that folder, if you prefer. If you installed Git and didn't change the default installation right-click in the folder will give you the option for Git Bash in the folder.
yarncommand. It will install all the required scripts. It will add a new folder
yarn compilecommand. It will compile again everything.
yarn watchcommand, leave the terminal open, and go to change Less variables. It will automatically compile every time you save any Less file belonging to the Zero One theme.
yarn watchis running, let's change some variables.