Examine source code of Good ol' Black

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#a3a3a3",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Good ol' Black",
  "manifest_version": 2,
  "description": "This is an all-black theme. Personally, I like mi browser in a dark mood but I really couldn't find any theme already created wich was actually 100% black; so here I am, and here's my theme."
}