userChome.css for Firefox Quantum. Multirow tabs

userChome.css

@namespace url('http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul');
 #TabsToolbar { 
   display: block !important;
 } 
:root {
  --tab-min-height: 23px !important;
}


/* Selectors for Firefox 71+ */
/* These are not tabs toolbar specific but horizontal scrollbox isn't used elsewhere, except in bookmarks toolbar but there it doesn't have [part] attribute since it's not in shadow-root */
@-moz-document url(chrome://browser/content/browser.xhtml){
  .scrollbutton-up[orient="horizontal"][part]~spacer,
  .scrollbutton-up[orient="horizontal"][part],
  .scrollbutton-down[orient="horizontal"][part]{ display: none }

  scrollbox[part][orient="horizontal"]{
    display: flex;
    flex-wrap: wrap;
    overflow-y: auto;
    max-height: calc(var(--tab-min-height) * var(--multirow-n-rows));
    scrollbar-color: currentColor transparent;
    scrollbar-width: thin;
  }
}

/* Test for Firefox > 66 */
@supports (inset-block:auto){
  #tabbrowser-tabs > .tabbrowser-arrowscrollbox > .arrowscrollbox-scrollbox{
    display: flex;
    flex-wrap: wrap;
    overflow-y: auto;
    max-height: calc(var(--tab-min-height) * var(--multirow-n-rows));
    scrollbar-color: var(--toolbar-bgcolor) var(--lwt-accent-color);
    scrollbar-width: thin;
  }
  #tabbrowser-tabs > .tabbrowser-arrowscrollbox {
    overflow: -moz-hidden-unscrollable;
    display: block;
  }
}

.toolbar-items {
   display: block !important;
}
.tabbrowser-tab:not([pinned]) {
  flex-grow: 1;
  /*   min-width: 140px; */
  border-bottom: 1px solid #c7c8c8 !important;
}
.tabbrowser-tab,
.tab-background {
  height: var(--tab-min-height);
}

.tab-content {
  padding-left: 2px !important;
  padding-right: 2px !important;
}
.tabbrowser-tab[pinned] {
  padding-left: 9px !important;
  padding-right: 9px !important;
}

/* .tabbrowser-tabs[closebuttons="activetab"] */
.tabbrowser-tab:not([pinned='true']):hover
  .tab-close-button:not([selected='true']) {
  display: -moz-box !important;
  height: 16px;
}

.tabs-newtab-button .toolbarbutton-icon {
  height: 15px !important;
  width: 15px !important;
  padding: 0 !important;
  padding-top: 1px !important;
}

.tab-stack {
  width: 100%;
}
#tabbrowser-tabs {
  --tab-min-width: 125px !important;
}
#tabbrowser-tabs .scrollbox-innerbox {
  display: flex;
  flex-wrap: wrap;
}
#tabbrowser-tabs .arrowscrollbox-scrollbox {
  overflow: visible;
  display: block;
}
#tabbrowser-tabs .scrollbutton-up,
#tabbrowser-tabs .scrollbutton-down,
#alltabs-button,
.tabbrowser-tab:not([fadein]) {
  display: none;
}
#main-window[sizemode='maximized'] #TabsToolbar {
  margin-left: var(--tab-min-height);
}