I've developed tons of Retool apps over the past 4 years or so and I never got my head around why ever Retool app felt the exact same regardless of theme.
I think its because of default container and canvas padding. In this example I set the padding to 320 px and to me it no longer feels like a Retool app but a normal portal.
Whitespace does wonders.
Does anyone else have any tips or tricks to make their Retool app feel a bit less like a classic Retool app and more like a full fledged portal?