Examine source code of Blue Theme

{
  "manifest_version": 2,
  "version": "2.0",
  "name": "Blue Theme",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-000-5672c42860d5b06e1058dc477397f3ef.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(25, 54, 90)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(10, 27, 50)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(10, 27, 50)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(25, 54, 90)",
      "popup": "rgb(25, 53, 90)",
      "popup_text": "rgb(255, 255, 255)",
      "icons_attention": "rgb(255, 255, 255)",
      "icons": "rgb(255, 255, 255)",
      "ntp_background": "rgb(25, 53, 90)",
      "ntp_text": "rgb(255, 255, 255)",
      "popup_border": "rgb(25, 53, 90)",
      "sidebar_highlight": "rgb(10, 27, 50)",
      "sidebar": "rgb(25, 53, 90)",
      "tab_selected": "rgb(25, 53, 90)",
      "tab_text": "rgb(255, 255, 255)",
      "toolbar_field_border_focus": "rgb(10, 27, 50)",
      "toolbar_field_highlight": "rgb(25, 54, 90)",
      "tab_loading": "rgb(25, 54, 90)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e0b9e2e3-bf28-460b-abd0-cf008008f664}"
    }
  }
}