Add a transition duration to show/hiding of components

I wanted to add some delays when showing or hiding components, and tried this snippet:

 ._qiZr9 {
  transition: opacity 2s ease-in !important;
  transition-duration: 2s;

I added in some options just to see if something works, but it does not like anything is working. Someone has tried this before?

I think Custom CSS doesnt support transitions or animations