Atom wants to look like an old notebook. Like this.
Notebook UI styles most core elements to make Atom feel right at home in the early centuries. Or in a videogame based in early centuries. Either way, it's what Atom wants.
Notebook UI is based entirely on Atom One Light UI which excels at blending UI styles with syntax theme colors, unlike other themes. Notebook UI's styles don't mesh with as many themes as Atom One but it looks great with probably all light or solarized syntax themes.
It also relies on Fira Code iScript for handwritten font styling.
Full-screen using Solarized Light. Atom icon remains in view, just like Atom always wanted.
Settings use rotated hues to help distinguish from other sections.
Find-in-project also uses different hues.
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.