A high contrast theme with nice, well-balanced colours.
Hyperion comes in standalone light and dark variants (see further info below).
The font is Iosevka term
The UI is Atom Material.
Search for hyperion-syntax
in Settings > Install > Themes. Or install it directly using the command:
apm install hyperion-syntax
Project page: https://protesilaos.com/hyperion
Hyperion dark version: https://atom.io/themes/hyperion-dark-syntax
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.