Standard Notes is an excellent end-to-end encrypted notes application. Over time, I developed several custom themes that have partially been included in the official Standard Notes Community Plugins repository.
They provide a variety of high-quality color palettes for different times of day and personal preferences.
Nord
An arctic, north-bluish color palette, based on the popular Nord theme.
Solarized Light
A beautiful, high-contrast light implementation of the classic Solarized color scheme.
Everlight
A familiar, clean interface that brings an Evernote-like aesthetic to Standard Notes.
Monokai Ristretto
A warm, coffee-inspired dark theme based on the Monokai palette, perfect for late-night writing.
All of these themes can be installed directly through the Standard Notes app or by using the extension JSON links provided in their respective repositories.