max-height: 0;
 overflow: hidden;
 transition: ease all 3s;

 max-height: 100vh;
 animation: 0s pop-in;
 animation-fill-mode: both;
 animation-delay: 2s;

 from {overflow: hidden}
 to {overflow: unset}

this was asked before by myself /questions/1284841 and again by another user /questions/1402855 the code was #navigator-toolbox { max-height: 0; overflow: hidden; transition: ease all 3s; } #main-window:hover #navigator-toolbox { max-height: 100vh; animation: 0s pop-in; animation-fill-mode: both; animation-delay: 2s; } @keyframes pop-in { from {overflow: hidden} to {overflow: unset} } the issue now i have with firefox 124.0.2 is that the transition is now instant when my mouse enters or leaves the window and one of my addon buttons (roboform) no longer works with this userchrome.css edit. its been a few updates ago it broke maybe 15 or so and now im wondering if there is a better updated script that works like it used to.