The material on the tank is 3/4", well the metric "equivalent" anyway - 18mm which is .708", just a tad above 11/16". With the exception of one domestic mfr (Polycast), whenever you ask your acrylic distributor for 3/4", you are gonna get 18mm.
Yes, you'd like to see thicker but that is the "industrial standard" for this size aquarium. As stated earlier, if properly - should be okay.
James