I Built the World's Most Customizable Scientific Calculator (30+ Themes, Python + PyQt6)

The idea Every OS ships a calculator. Every one of them looks the same, feels the same, and disappears from memory the moment you close it. So I built ACALCU v3 — an Akhouri Systems product — a scientific calculator that's absurdly, unnecessarily customizable. Not because a calculator needs 30+ themes and per-button styling, but because it was a fun constraint to design around: how far can you push a "boring" utility app before it becomes something people actually enjoy using? What it does At its core, ACALCU is a standard scientific calculator: basic arithmetic, sin, cos, tan, log, √, π, percentages, and a running expression engine built on Python's math module. On top of that core, it layers: 30+ built-in themes — Royal, Liquid Glass, Wild, Cyberpunk, Dracula, Nord, Solarized, Monokai, Windows 7 / Vista / 10, OneUI 8.0, Matrix, Rose Gold, Galaxy, Fire, Ice, Neon, Vintage, Sakura, Midnight, Forest, Candy, Terminal, Gold Dark, and more. Per-button customization — right-click any button to change its color, font, or set a custom image/video as its background. Every button on the grid is independently styleable. A live "Wild" theme — a small animated plant widget that visibly grows every time you run a calculation. Calculation history — a scrollable dialog of your last 50 calculations. Persistent config — every customization is saved to a local JSON file and reloaded on next launch. Full keyboard support — number keys, operators, Enter/Escape, all mapped to the same input pipeline the buttons use. Architecture The whole thing is a single-file PyQt6 desktop app, structured around a few core pieces: python THEMES = { "DEFAULT": { "app_bg": "#0a0a0a", "display_bg": "#111111", ... }, "ROYAL": { "app_bg": "#0a0800", "display_fg": "#ffd700", ... }, "LIQUID_GLASS": { "app_bg": "transparent", ... , "transparent": True }, # ...30+ more } Each theme is just a dict of colors, font, corner radius, and optional flags (transparent, wild). The Config class resolves the active theme