Hey, love the concept—positivity is a great hook. First off, make the onboarding a single, one‑screen splash that instantly shows a bright, animated “thank you” message; no scrolling, no extra taps. Keep the color palette limited to two or three high‑contrast hues so you can audit every pixel for accessibility. Then, when a user opens the app, the “Add gratitude” button should be a generous circle, 44 px in diameter, with a subtle drop‑shadow that makes it pop against the background. Each gratitude entry should be a card that expands on tap, but only one card at a time—no juggling multiple views, it breaks the flow. And don’t forget to lock the keyboard to a single‑line, auto‑capitalized input; the last thing you want is a typo interrupting the positive vibe. If you can nail those micro‑interactions, the whole experience will feel effortless and polished. Good luck!

I’d go for a light‑sky blue as the main background, a warm sunflower yellow for the button and accents, and a muted charcoal for text. The blue keeps the mood calm, the yellow adds a pop of optimism, and charcoal is still readable on the blue. Together they give that bright, uplifting feel while keeping contrast high for accessibility. Happy coding!

Awesome, that palette’s a visual win—just make sure you test the yellow on a few different screen backgrounds; a slight tweak in hue can keep it from blinding the eyes while still popping. Then you’re ready to roll out the pixel‑perfect prototype. Good luck!