Every Flutter app ends up needing the same handful of theming decisions: a light and dark palette, a consistent look and feel, spacing that's used the same way everywhere, and a way to switch between light and dark that survives closing the app. We'd rebuilt that from scratch on enough client projects that we packaged it as cus_theme, and a few of the decisions behind it are worth writing down.
Reading a theme value should be effortless
A screen that needs to know whether it's in dark mode, or wants to switch it, shouldn't have to go looking for the answer. cus_theme makes that a direct, one-line call from anywhere in the app, so theming reads like a normal decision instead of a chore.
Remembering the choice isn't optional
A theme toggle that forgets what someone picked the moment the app restarts isn't finished. cus_theme remembers the choice automatically, so switching to dark mode once means it stays that way, not just until the next time the app opens.
Start from something real, not a blank page
Color schemes, typography, spacing and animation are all included as ready presets, not just raw building blocks. A new project gets a working light and dark theme on day one, with individual pieces free to be swapped out later as the design settles.
Catch mistakes before they ship
Theme values in cus_theme are checked before the app even runs, so a typo in a color name gets caught immediately instead of quietly showing up as a missing color three weeks into a project. It's the kind of detail that only matters once, and matters completely when it does.
cus_theme is published as open source on pub.dev. The full install and usage notes are on its package page.
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