Examine source code of seiba

{
  "name": "seiba",
  "manifest_version": 2,
  "version": "2.0",
  "theme": {
    "images": {
      "theme_frame": "seiba_dark_header.png"
    },
    "colors": {
      "frame": "rgba(29, 27, 25, 1)",
      "tab_background_text": "rgba(252, 238, 217, 1)",
      "toolbar": "rgba(29, 27, 25, 1)",
      "bookmark_text": "rgba(252, 238, 217, 1)",
      "toolbar_field": "rgba(29, 27, 25, 1)",
      "toolbar_field_text": "rgba(252, 238, 217, 1)",
      "tab_line": "rgba(252, 238, 217, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f5b2fb3a-30f0-4e1a-a071-fc333a8e471e}"
    }
  }
}