The dark UI isn't aesthetic. It's functional. When you're reviewing weekly spending at 11pm, your eyes need low-strain contrast that still makes the data pop.
The category cards sit below the chart for a reason. The chart answers "how much did I spend this week?" The cards answer "where did it go?"
Finance apps either look sterile or playful. This needed to feel like neither - it needed to feel powerful. Like your money is being managed by something that takes it seriously.
"Track your spending with confidence." Confidence. That word choice shaped every design decision.