dark fox

userChrome.css

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");

:root:-moz-lwtheme-brighttext {
  --chrome-background-color: #424242 !important;
  --chrome-color: #8f8f8f !important;
  --chrome-secondary-background-color: #363636 !important;
  --toolbox-border-bottom-color: #333333 !important;
  --url-and-searchbar-border-color: #333333 !important;
  --focus-ring-box-shadow: #191917 !important;
  --url-and-searchbar-background-color: #363636 !important;
}

@-moz-document url(chrome://browser/content/browser.xul) {
  #main-window, browser[type="content-primary"], browser[type="content"], tabbrowser#content, #content, browser[type="content"]>html {
    background: #323234 !important;
  }
  .downloadDetailsNormal {
    display: none !important;
  }
  .downloadDetailsFull {
    display: inline !important;
  }
  richlistitem[type="download"]:hover>.downloadMainArea>.downloadContainer>.downloadDetailsFull {
    display: none !important;
  }
  #TabsToolbar {
    visibility: collapse !important;
  }
  #sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"] #sidebar-header {
    display: none;
  }
  #sidebar {
    min-width: 100px !important;
  }
  #aHTMLTooltip {
    display: none !important
  }
}

/* Remove white flash on tab load */

.browserContainer {
  background-color: #363636 !important;
}


/* Address bar focus styles */

#urlbar[focused="true"], .searchbar-textbox[focused="true"] {
  border-color: #444444 !important;
  background-color: #363636 !important;
}


/* Remove top border of selected tab */

:root:-moz-lwtheme {
  --tab-line-color: none !important;
}


/* Fixing container tab borders */

[data-identity-color="blue"] {
  --identity-tab-color: #7193F7 !important;
  --identity-icon-color: #7193F7 !important;
}

[data-identity-color="green"] {
  --identity-tab-color: #71F78A !important;
  --identity-icon-color: #71F78A !important;
}

[data-identity-color="orange"] {
  --identity-tab-color: #F2DE73 !important;
  --identity-icon-color: #F2DE73 !important;
}

[data-identity-color="pink"] {
  --identity-tab-color: #F771E7 !important;
  --identity-icon-color: #F771E7 !important;
}


/* Make normal density theme bit compact */

:root:not([uidensity=compact]) #back-button {
  padding-top: 0 !important;
  padding-bottom: 0 !important;
}

:root:not([uidensity=compact]) #back-button>.toolbarbutton-icon {
  background-color: unset !important;
  border: none !important;
}

userContent.css

browser[type="content-primary"], tabbrowser tabpanels, #appcontent>#content {
  background-color: #282828 !important;
}

@-moz-document url("about:newtab"), url("about:blank") {
  /* Dark backgound */
  body {
    background: #333030 !important;
  }
}

@-moz-document url("about:newtab") {
  /* Invert icons color to white */
  .icon, .info-option-icon, .block-snippet-button, #onboarding-overlay-close-btn {
    -webkit-filter: invert(100%);
  }
  .icon-pin-small, .icon-topsites {
    -webkit-filter: invert(0);
  }
  /* Dark background when hovering above the settings icon, color is inverted */
  .prefs-button:hover {
    background-color: #BDBDBD !important;
  }
  /* Dark backgound for all pop-ups */
  .sidebar, .actions, .options, .card-outer, .info-option, .context-menu, #onboarding-overlay-dialog, #snippets-container {
    background: #212121 !important;
    border-color: #727272 !important;
  }
  /* Give top border to snippet */
  #snippets-container {
    border-top: 2px solid #727272 !important;
  }
  /* Dark backgound color when highlight preview image didnt load */
  .card-preview-image-outer {
    background-color: #181818 !important;
  }
  /* Make backgound darker instead of brighter when clicking on firfox tour */
  #onboarding-overlay {
    background-color: rgba(20, 20, 20, 0.9) !important;
  }
  /* Texts */
  h1, h4, span, #onboarding-header {
    color: #EEE !important;
  }
  p {
    color: #CCC !important;
  }
  .card-host-name {
    color: #AAA !important;
  }
  /* Ignore search autocomplete pop-up */
  #searchSuggestionTable span {
    color: black !important;
  }
}

@-moz-document url("about:addons") {
  #addon-list>scrollbox {
    padding-right: 0 !important;
    padding-left: 0 !important;
  }
  /* Remove "Get Add-ons" from sidebar and addon descriptions */
  #category-discover, .advancedinfo-container {
    display: none !important;
  }
  /* Remove unneeded space above addons */
  #header {
    margin-top: 10px !important;
    margin-bottom: 10px !important;
  }
  .addon {
    padding: 0px !important;
  }
  .addon>.pending, .addon>.error, .addon>.warning {
    margin-inline-start: 8px !important;
  }
  .icon-container {
    margin: auto !important;
    height: auto !important;
    width: auto !important;
    padding-inline-start: 5px !important;
  }
  .icon-container>.icon {
    max-height: 22px !important;
  }
  button {
    min-height: auto !important;
  }
}

@-moz-document url-prefix(about:blank), url-prefix(about:newtab) {
  html:not(#ublock0-epicker), html:not(#ublock0-epicker) body, #newtab-customize-overlay {
    background: #323234 !important;
  }
}

@-moz-document url(about:newtab), url(about:home) {
  body {
    background-color: #323234 !important;
    color: #D1D1D1 !important;
  }
  .card, .prefs-pane .sidebar {
    background-color: #202020 !important;
  }
  #snippets, .section-title, .snippetContainer {
    color: #AEAEAE !important;
  }
  .contentSearchSuggestionTable, .contentSearchSuggestionsList {
    color: black!important;
  }
  .display-item {
    color: #D1D1D1 !important;
  }
  #aboutMozilla::before {
    filter: invert(100%) !important;
  }
  #searchText {
    background: #474749 !important;
    border-radius: 4px;
    border: 1px solid #262627;
    box-shadow: none;
  }
  #searchSubmit, #launcher {
    display: none !important;
  }
}
@-moz-document url(about:newtab) {
    .activity-stream {
        background-color: #363636 !important;
    }
    .top-sites-list .top-site-outer > a {
        color: #737373 !important;
    }
    .top-sites-list .top-site-outer .title.pinned span {
        font-size: smaller !important;
    }
    .tile {
      filter: grayscale(42%) !important;
      opacity: .9 !important;
    }
}