Examine source code of soft blue grid

{
  "manifest_version": 2,
  "version": "3.0",
  "name": "sbg v3",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-005-f5f3cf677b1f132c75ddc7bd319dd1fc.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(90, 100, 150, 0.67)",
      "toolbar_text": "rgb(182, 184, 219)",
      "frame": "rgb(48, 58, 106)",
      "tab_background_text": "rgb(182, 184, 219)",
      "toolbar_field": "rgb(182, 184, 219)",
      "toolbar_field_text": "rgb(48, 58, 106)",
      "tab_line": "rgb(182, 184, 219)",
      "popup": "rgb(182, 184, 219)",
      "popup_text": "rgb(48, 58, 106)",
      "button_background_active": "rgb(48, 58, 106)",
      "button_background_hover": "rgb(48, 58, 106)",
      "frame_inactive": "rgba(90, 100, 150, 0.67)",
      "icons_attention": "rgb(48, 58, 106)",
      "icons": "rgb(182, 184, 219)",
      "ntp_background": "rgb(53, 62, 101)",
      "ntp_text": "rgb(182, 184, 219)",
      "popup_border": "rgb(48, 58, 106)",
      "popup_highlight_text": "rgb(182, 184, 219)",
      "popup_highlight": "rgb(90, 100, 150)",
      "sidebar_border": "rgb(48, 58, 106)",
      "sidebar_highlight_text": "rgb(182, 184, 219)",
      "sidebar_highlight": "rgb(48, 58, 106)",
      "sidebar_text": "rgb(182, 184, 219)",
      "sidebar": "rgb(90, 100, 150)",
      "tab_loading": "rgb(182, 184, 219)",
      "tab_text": "rgb(182, 184, 219)",
      "toolbar_bottom_separator": "rgb(48, 58, 106)",
      "toolbar_field_border_focus": "rgb(182, 184, 219)",
      "toolbar_field_border": "rgb(48, 58, 106)",
      "toolbar_field_highlight": "rgb(48, 58, 106)",
      "toolbar_field_separator": "rgb(48, 58, 106)",
      "toolbar_top_separator": "rgb(48, 58, 106)",
      "toolbar_vertical_separator": "rgba(90, 100, 150, 0.67)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{3a98bc77-985e-4b8f-908c-6bbfc80ca236}"
    }
  }
}