Examine source code of Google Sheets

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Google Sheets",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(255, 255, 255)",
      "toolbar_text": "rgb(95, 99, 104)",
      "frame": "rgb(24, 128, 56)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(241, 243, 244)",
      "toolbar_field_text": "rgb(95, 99, 104)",
      "tab_line": "rgba(251, 188, 4, 0)",
      "popup": "rgb(255, 255, 255)",
      "popup_text": "rgb(32, 33, 36)",
      "button_background_active": "rgb(230, 244, 234)",
      "ntp_background": "rgb(230, 244, 234)",
      "sidebar_border": "rgb(24, 128, 56)",
      "sidebar_text": "rgb(24, 128, 56)",
      "sidebar": "rgb(255, 255, 255)",
      "tab_text": "rgb(24, 128, 56)",
      "toolbar_bottom_separator": "rgba(255, 255, 255, 0)",
      "toolbar_field_border": "rgba(207, 228, 217, 0)",
      "toolbar_field_focus": "rgb(255, 255, 255)",
      "toolbar_top_separator": "rgba(255, 255, 255, 0)",
      "tab_loading": "rgba(251, 188, 4, 0)"
    }
  }
}