Create .env file with such content:
BASE_REPO_URL=https://raw.githubusercontent.com/<username>/<repo-name>/<branch>
Run
yarn install
yarn start
Site should be available at http://localhost:1234/ address
On build server you should define environment variable BASE_REPO_URL
.
E.g:
BASE_REPO_URL=https://raw.githubusercontent.com/<username>/<repo-name>/<branch>