Change themes and icons Grafana

good day

I would like to know the method to modify grafana themes from a standard installation in Debian, currently the server where it is installed has no nodejs / yarn, so I would like to know if there is a way to make changes to the themes without having to make a rebuild.

Beforehand thank you very much.

if you built from sources and you want to rebuild you can just run
./node_modules/webpack/bin/webpack.js --progress --colors --mode development --config scripts/webpack/