I've spent roughly a decade working in multiple scales, resolutions and ratios.
I've dealt with Android, with it's 57,000 different possible resolutions. I've handled iOS with portrait/landscape orientations. I've coped with Windows with a bazillion different possible window sizes..

But 3DS, with one single screen resolution!?!
AARGH!!!

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The problem is, of course, down to me having changed my Virtual Resolution.
For years I've worked within a more-or-less static 800x600 area (with the Y scale being dependent on the screen's resolution), then scaled all the numbers to fit neatly within whatever resolution I'm aiming for.

But for 3DS, I've changed the virtual resolution down so that it matches exactly with the top-screen. 400x240
For the most-part, all my usual numbers scale well enough, but it also means I can plot precise pixels on the screen, and have exact 1:1 sprites in specific locations.

But the change in virtual resolution is hammering home just how much I need to re-learn virtual scaling techniques.
I've become so used to having the screenspace of 800x? available that I've gotten quite a bit lazy in my techniques.

This week's game is most definitely showing that up, as I'm battling with all of the scaling, in a bid to make it work in a vaguely passable way.

I guess I'm going to have to do a lot of retraining in this department, in order to get back to full speed.

Maybe I need to make another Testcard? That's usually helped me in the past.