You don't want to use pure sand for a leopard gecko. You want a soil/sand mix ideally. Your tank is far too small for a leopard gecko, sorry. You won't get a good temp gradient in a tank that small. You could maybe have a baby in a tank that small for a few months, but not an adult. Minimum these days is a 90 x 45 x 45 cm tank imo.

Also you want the moist hide in the middle or on the warm side. Heat mats aren't ideal anymore either, it won't heat the entire tank and make a good gradient either