Updated 11/25/16 - Improvements to images.
Most of the dark themes I tried using were distracting and overly colorful and contrast heavy, especially with PHP embedded into HTML. The New Moon theme strives to remedy that, with a theme that is pleasant to view in any language.
File > Extension Manager
The code is open source and available under the MIT License.
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.