Building all.css file for istio.io

I am wondering how I can watch and rebuild the all.css file every time a change is made to the scss files in the istio.io.

First of all it seems that sass folder and its content is in the unwatched src folder. If I move the sass folder to the watched assets folder the changes are detected but the all.css file isn’t built.

“make serve” command seems to generate the file on the local server launch but that’s about it. The changes to the scss files are not visible on the screen.

I am wondering how can I possibly make the scss changes and possibly re-run the gen_site.sh which generates the css file.