Give the web site address for the school in "PA" state with the highest latitude.
web site address refers to site; PA refers to state_abbr = 'PA'; highest latitude refers to MAX(lat_y);
SELECT DISTINCT T1.site FROM institution_details AS T1 INNER JOIN state_sector_grads AS T2 ON T2.state = T1.state WHERE T2.state_abbr = 'PA' AND T1.lat_y = ( SELECT MAX(T1.lat_y) FROM institution_details AS T1 INNER JOIN state_sector_grads AS T2 ON T2.state = T1.state WHERE T2.state_abbr = 'PA' )