/* Source file https://github.com/MrOtherGuy/firefox-csshacks/tree/master/chrome/centered_tab_content.css made available under Mozilla Public License v. 2.0 See the above repository for updates as well as full license text. */ .tab-content:not([pinned])::before{ display: -moz-box; content: ""; -moz-box-flex: 1; }