The planning and development services director is authorized to create and administer, design guidelines for the Griffin Overlay District. These standards shall provide acceptable architectural design controls, landscaping, detail drawings, signage, fencing, lighting, street and site furniture and grating. These standards shall be used to promote proper design criteria for the overlay district and shall guide the planning director in deciding whether a proposed design complies with the requirements of this overlay district. The Design Guidelines are hereby made a part of this ordinance and shall be amended from time to time.