In ISA conditions the altitude at Marseille would be 10,000 – 30 = 9,970ft and at Palma it would be 10,000 – (7 x 30) = 9,790 ft. Since the aircraft are at the same true altitude the air at Palma is warmer than the air at Marseille.

 FL100 = 700hPa. The same true altitude at both locations but that vertical distance has 312hPa at Marseille and only 306hPa at Palma. It's "more feet per hPa" at Palma because it's warmer.