Cannot Compile Example: No rule to make target

[l3x]

on Manjaro Linux
following 5min tutorial for ocaml-start :
https://github.com/ocsigen/ocsigen-start/blob/master/template.distillery/README.md

make db-init -> ok
make db-create -> ok
make db-schema -> ok

make db-init -> ok
make db-create -> ok
make db-schema -> ok
make test.byte -> ok

sudo make install
[WARNING] Running as root is not recommended
[WARNING] Running as root is not recommended
install local/lib/todo/todo.cma /usr/local/lib/todo
make: *** No rule to make target '/root/.opam/default/share/ocsigen-toolkit/css/ot_buttons.css', needed by 'static/css/.import-external-css'.  Stop.