If you're having trouble seeing the tiles in your hidden zones and don't always want to use Alt to look at the cards, you can turn down/off the opacity of hidden zones in your settings by going to Menu -> Configuration -> Interface -> Misc. Settings and change the 'Hidden Zone Show Opacity' to your desired opacity. You can also find the settings to lower the opacity of hidden zones you can't see in if you don't like the look of random colored blocks in your game!