The high-level folder structure looks as follows:
/
├── documentation/
├── public/
├── src/
│ ├── js/
│ └── scss/
├── ...(config files)
└── README.md
All gulp compilated projects assets go here: css and js. Do not make any adjustments here, as these will be overwritten anyway.
The asset source codes. The right place to do your work.