Examine source code of Self_use_darker_theme

{
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-0.svg"
      ]
    },
    "colors": {
      "frame": "#3c3c3c",
      "frame_inactive": "#3c3c3c",
      "tab_background_text": "#c0c0c0",
      "toolbar": "#5c5c5c",
      "tab_selected": "#5c5c5c",
      "tab_text": "#ffffff",
      "ntp_text": "#000000",
      "sidebar": "#3c3c3c",
      "sidebar_highlight": "#8d8d8d",
      "sidebar_highlight_text": "#3c3c3c",
      "sidebar_text": "#c0c0c0",
      "tab_background_separator": "#8d8d8d",
      "button_background_active": "#3c3c3c",
      "icons": "#c0c0c0",
      "button_background_hover": "#3c3c3c",
      "icons_attention": "#ff8040",
      "popup": "#3c3c3c",
      "popup_highlight": "#c0c0c0",
      "popup_border": "#5c5c5c",
      "popup_text": "#c0c0c0",
      "popup_highlight_text": "#c0c0c0",
      "tab_loading": "#ff8040",
      "tab_line": "#c0c0c0",
      "toolbar_bottom_separator": "#5c5c5c",
      "toolbar_field": "#282828",
      "toolbar_field_border": "#5c5c5c",
      "toolbar_field_border_focus": "#3c3c3c",
      "toolbar_field_text": "#c0c0c0",
      "toolbar_field_text_focus": "#8d8d8d",
      "toolbar_field_separator": "#ff8040",
      "bookmark_text": "#c0c0c0",
      "toolbar_top_separator": "#5c5c5c",
      "toolbar_vertical_separator": "#ff8040"
    }
  },
  "name": "Self_use_darker_theme",
  "manifest_version": 2,
  "version": "1.1",
  "description": "Self-use themes. Including sidebars also darkened"
}