Firefox style configuration

sidebery.css

@media (prefers-color-scheme: dark), (prefers-color-scheme:no-preference) {
    #root[data-style="auto"] {
        --bg: #000;
        --border-fg: #0c0c0c;
        --nav-btn-activated-bg: #0c0c0c;
        --tabs-bg-active: #101010;
        --tabs-activated-bg: #0c0c0c;
        --tabs-bg-hover: #080808;
    }
}

#root[data-style="auto"] {
    --tabs-height: 27px;
}

.panels-box, .panel-btn {
    height: 34px !important;
}

userChrome.css

#TabsToolbar
{
    visibility: collapse;
}

#sidebar-header {
	display: none;
}

:root {
  --toolbar-field-focus-border-color: #8c64dd !important;
}

.sidebar-splitter {
  width: 3px !important;
}

/*** BEGIN Firefox 77 (June 2, 2020) Override URL bar enlargement ***/

  /* Compute new position, width, and padding */

  #urlbar[breakout][breakout-extend] {
    top: 5px !important;
    left: 0px !important;
    width: 100% !important;
    padding: 0px !important;
  }
  /* for alternate Density settings */
  [uidensity="compact"] #urlbar[breakout][breakout-extend] {
    top: 3px !important;
  }
  [uidensity="touch"] #urlbar[breakout][breakout-extend] {
    top: 4px !important;
  }

  /* Prevent shift of URL bar contents */

  #urlbar[breakout][breakout-extend] > #urlbar-input-container {
    height: var(--urlbar-height) !important;
    padding: 0 !important;
  }

  /* Do not animate */

  #urlbar[breakout][breakout-extend] > #urlbar-background {
    animation: none !important;;
  }

  /* Remove shadows */

  #urlbar[breakout][breakout-extend] > #urlbar-background {
    box-shadow: none !important;
  }

/*** END Firefox 77 (June 2, 2020) Override URL bar enlargement ***/

toolbarbutton {
  padding: 0 !important;
}

.search-one-offs {
  padding-top: 2px !important;
  padding-bottom: 3px !important;
}

/* Change font size of URL bar */
#urlbar-container {
  font-size: 15px !important;
}

@media (prefers-color-scheme: dark) {
  :root {
    --toolbar-non-lwt-bgcolor: #000 !important;
    --toolbar-field-border-color: #0c0c0c !important;
  }
  
  #urlbar-background, #searchbar {
    background-color: #0c0c0c !important;
  }
  
  #navigator-toolbox {
    border-color: #0c0c0c !important;
  }
  
  .sidebar-splitter {
    background-color: #0c0c0c !important;
    border-color: #0c0c0c !important;
  }
}

@media (prefers-color-scheme:light) {
  .sidebar-splitter {
    border-color: #cccccc !important;
  }
}

userContent.css

@-moz-document url-prefix("about:newtab"), url-prefix("about:home"), url-prefix("about:blank"), url-prefix("about:preferences"), url-prefix("about:debugging"), url-prefix("about:addons") {
    @media (prefers-color-scheme: dark) {
        :root {
            --newtab-background-color: #000 !important;
            --newtab-background-color-secondary: #0c0c0c !important;
            --in-content-page-background: #000 !important;
            --in-content-background-color: #000 !important;
            --in-content-box-background: #0c0c0c !important;
        }
    }

    :root {
        --in-content-accent-color: #8c64dd !important;
        --in-content-primary-button-background: #8c64dd !important;
        --newtab-primary-action-background: #8c64dd !important;
        --color-accent-primary: #8c64dd !important;
        --color-accent-primary-hover: #9b7ade !important;
        --color-accent-primary-active: #8c64dd !important;
        --in-content-primary-button-background-hover: #9b7ade !important;
        --in-content-primary-button-background-active: #8c64dd !important;
        --in-content-primary-button-text-color: #ffffff !important;
    }
}