One Dark — Codex app theme

One Dark was the default theme of Atom, GitHub's editor, and it outlived its host — Atom was retired in 2022, but the palette had already escaped into every editor and terminal that mattered. It's easy to see why it stuck. Nothing in it is extreme: a gray-blue #282c34 base, evenly weighted accents, comments that recede without vanishing. It's the theme equivalent of a well-made office chair.

That neutrality is an asset in agent work. Sessions mix prose, shell output, diffs and errors, and One Dark treats them all with the same even hand — the coral red flags failures clearly but doesn't panic, the green reads as 'added' at a glance. You can stare at it for a full workday and hold no opinion about it by the end, which for a tool is close to the highest praise available.

Pick it when you want zero adjustment period — anyone who has spent time in Atom, or in the One Dark Pro port that remains one of the most-installed VS Code themes, carries these color associations already. It's also the safest recommendation for a teammate who claims not to care about themes: they'll never notice it, and never fight it either, which is exactly the point.