mobile-config-firefox/chrome/normal_pinned_tabs.css

/* Source file https://github.com/MrOtherGuy/firefox-csshacks/tree/master/chrome/normal_pinned_tabs.css made available under Mozilla Public License v. 2.0
See the above repository for updates as well as full license text. */

/* Makes pinned tabs behave like normal tabs, making their title and close buttons visible and making them "non-positioned" when tab strip is overflowing */

#tabbrowser-tabs{ padding-inline-start: 0px !important }

.tabbrowser-tab{
  -moz-box-flex: 100;
  max-width: 225px;
  min-width: var(--tab-min-width);
  width: 0;
  transition: min-width 100ms ease-out, max-width 100ms ease-out;
  margin-inline-start: 0px !important;
  position: initial !important;
  display: -moz-box !important
}

.tabbrowser-tab[pinned] > .tab-stack{ border: none !important; }
.tabbrowser-tab[pinned]::after{ position: static !important; margin-block: 0px 1px !important; }

.tabbrowser-tab[selected]{ position: relative !important; }

.tab-label-container{ width: unset !important; }
.tab-label-container[pinned]{ margin-inline-start: 8px }

.tab-icon-sound:is([soundplaying],[muted],[activemedia-blocked],[pictureinpicture]),

.tab-icon-overlay{ display: none !important; }

#tabbrowser-tabs[closebuttons="activetab"] > #tabbrowser-arrowscrollbox > .tabbrowser-tab > .tab-stack > .tab-content > .tab-close-button:not([selected="true"]){ display: none !important; }

/* Comment out or remove this if you want pinned tabs to never have close-button */
.tab-close-button{ display: -moz-box !important; }