Examine source code of Sleek Steam

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Sleek Steam",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(42, 46, 54)",
      "toolbar_text": "rgb(185, 188, 191)",
      "frame": "rgb(24, 29, 36)",
      "tab_background_text": "rgb(140, 141, 143)",
      "toolbar_field": "rgb(42, 46, 54)",
      "toolbar_field_text": "rgb(185, 188, 191)",
      "tab_line": "rgba(192, 192, 192, 0)",
      "popup": "rgb(62, 68, 79)",
      "popup_text": "rgb(220, 222, 223)",
      "ntp_background": "rgb(24, 29, 36)",
      "popup_border": "rgba(255, 255, 255, 0.21)",
      "sidebar_text": "rgb(185, 188, 191)",
      "sidebar": "rgb(42, 46, 54)",
      "tab_selected": "rgba(71, 94, 174, 0)",
      "tab_text": "rgb(255, 255, 255)",
      "toolbar_bottom_separator": "rgba(34, 25, 77, 0)",
      "toolbar_top_separator": "rgba(255, 255, 255, 0)",
      "tab_loading": "rgba(192, 192, 192, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4e3091de-2854-405e-8c05-2e276b1f4642}"
    }
  }
}