Examine source code of Blue theme

{
  "manifest_version": 2,
  "version": "1.2",
  "name": "Blue theme",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "frame": "rgb(30, 70, 140)",
      "toolbar": "rgb(40, 95, 180)",
      "toolbar_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(40, 65, 105)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_text": "rgb(255, 255, 255)",
      "tab_background_text": "rgb(210, 210, 210)",
      "tab_line": "rgb(160, 210, 255)",
      "tab_loading": "rgb(160, 210, 255)",
      "icons_attention": "rgb(255, 215, 0)",
      "popup": "rgb(40, 95, 180)",
      "popup_text": "rgb(255, 255, 255)",
      "popup_highlight": "rgba(255, 255, 255, 0.1)",
      "sidebar": "rgb(45, 45, 45)",
      "ntp_background": "rgb(45, 45, 45)",
      "ntp_text": "rgb(255, 255, 255)",
      "ntp_card_background": "rgb(60, 60, 60)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{0ac139ca-3615-497a-b42f-269561ca050b}"
    }
  }
}