zammad/app/frontend/apps/desktop/styles/transitions.css

.fade-enter-active,
.fade-leave-active {
  transition: opacity 0.3s ease;
}

.fade-enter-from,
.fade-leave-to {
  opacity: 0;
}

.fade-absolute-enter-active,
.fade-absolute-leave-active {
  transition: opacity 0.3s ease;
}

.fade-absolute-enter-from,
.fade-absolute-leave-to {
  position: absolute;
  opacity: 0;
}

.fade-up-enter-active,
.fade-up-leave-active {
  transition:
    opacity 0.3s ease,
    transform 0.3s ease-in-out;
}

.fade-up-enter-from,
.fade-up-leave-to {
  opacity: 0;
  transform: translateY(0.3rem);
}

.fade-move-enter-active,
.fade-move-move,
.fade-move-leave-active {
  transition: opacity 0.5s ease;
}

.fade-move-leave-active {
  position: absolute;
  top: -100%; /*  Add overflow clip on parent to hide elements */
}

.fade-move-enter-from,
.fade-move-leave-to {
  opacity: 0;
}

.collapse-enter-active,
.collapse-leave-active {
  transition:
    height 0.2s ease-in-out,
    opacity 0.2s ease;
  overflow: hidden;
}

.collapse-enter-from,
.collapse-leave-to {
  opacity: 0;
}

.pseudo-transition-enter-active,
.pseudo-transition-leave-active {
  transition: transform 0.3s ease;
}

.pseudo-transition-enter-from,
.pseudo-transition-leave-to {
  transform: translateY(0);
}

.slide-down-enter-active,
.slide-down-leave-active {
  transition: transform 0.2s ease;
}

.slide-down-enter-from,
.slide-down-leave-to {
  transform: translateY(-100%);
}