This page should be an index of design rules:
https://gf180mcu-pdk.readthedocs.io/en/latest/physical_verification/design_manual/drm_07.html
The design rules are very difficult to find. They are only accessible through an expandable left menu like so:

There should be an entry point page that has a list of design layers so that you can click to a specific set of design rules much like the other sky130 PDK:
https://antmicro-skywater-pdk-docs.readthedocs.io/en/latest/rules.html
This page should be an index of design rules:
https://gf180mcu-pdk.readthedocs.io/en/latest/physical_verification/design_manual/drm_07.html
The design rules are very difficult to find. They are only accessible through an expandable left menu like so:

There should be an entry point page that has a list of design layers so that you can click to a specific set of design rules much like the other sky130 PDK:
https://antmicro-skywater-pdk-docs.readthedocs.io/en/latest/rules.html