@media not (-moz-bool-pref: "zen.view.sidebar-expanded") {
  & .tabbrowser-tab {
    &:not([pinned]) {
      &:hover .tab-icon-stack {
        margin-left: 7px;
      }

&:hover .tab-close-button {
        position: absolute !important;
        display: block !important;
        padding: 5px !important;
        height: 18px !important;
        width: 18px !important;
        border-radius: 50% !important;
        margin-inline-end: 0 !important;
        margin-left: -9px;
        margin-top: -18px;
        background-color: var(--zen-main-browser-background) !important;
        cursor: pointer;
      }
    }
  }
}