Examine source code of Yotsuba B Custom

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Yotsuba B Custom",
  "theme": {
    "colors": {
      "frame": "#D6DAF0",
      "tab_background_text": "#4F5F73",
      "toolbar": "#D6DAF0",
      "bookmark_text": "#34345C",
      "toolbar_field": "#EEF2FF",
      "toolbar_field_text": "#34345C",
      "toolbar_top_separator": "#34345C",
      "toolbar_vertical_separator": "#B7C5D9",
      "tab_line": "#9181c9",
      "tab_selected": "#EEF2FF",
      "tab_text": "#34345C",
      "button_background_hover": "#B7C5D9",
      "button_background_active": "#9181c9",
      "popup": "#D6DAF0",
      "popup_text": "#34345C",
      "popup_highlight": "#9181c9",
      "popup_highlight_text": "#000000"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1a562a6c-c9cf-485e-ba8b-2f9c48ddb3e7}"
    }
  }
}