Examine source code of Green Matte

{
  "name": "Green Matte",
  "manifest_version": 2,
  "version": "4.0",
  "theme": {
    "images": {
      "theme_frame": "solid-color-image.png"
    },
    "colors": {
      "frame": "rgba(28, 34, 40, 1)",
      "tab_background_text": "rgba(240, 231, 231, 1)",
      "toolbar": "rgba(62, 74, 83, 1)",
      "bookmark_text": "rgba(240, 231, 231, 1)",
      "toolbar_field": "rgba(28, 34, 40, 1)",
      "toolbar_field_text": "rgba(240, 231, 231, 1)",
      "tab_line": "rgba(35, 43, 50, 1)"
    }
  }
}