Examine source code of Mild Dark Theme

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Mild Dark Theme",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(0, 0, 0, 0)",
      "toolbar_text": "rgb(120, 120, 120)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(87, 87, 87)",
      "toolbar_field": "rgba(0, 0, 0, 0)",
      "toolbar_field_text": "rgb(149, 149, 149)",
      "tab_line": "rgba(0, 0, 0, 0)",
      "popup": "rgb(27, 49, 60)",
      "popup_text": "rgb(255, 255, 255)",
      "button_background_active": "rgba(255, 255, 255, 0)",
      "frame_inactive": "rgb(55, 55, 55)",
      "icons_attention": "rgb(169, 169, 169)",
      "icons": "rgb(55, 55, 55)",
      "ntp_text": "rgb(55, 55, 55)",
      "popup_border": "rgba(55, 55, 55, 0)",
      "popup_highlight_text": "rgb(55, 55, 55)",
      "tab_loading": "rgba(0, 0, 0, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{999d81fe-28a1-42ff-b6a2-73c05d112190}"
    }
  }
}