vuepress-theme-system/styles/transitions.css

a vuepress theme

.transition-bottom-enter-active,
.transition-bottom-leave-active,
.transition-fade-enter-active,
.transition-fade-leave-active,
.transition-top-enter-active,
.transition-top-leave-active,
.transition-top-enter-active .pophover,
.transition-top-leave-active .pophover {
  transition: all 0.5s;
}

.transition-bottom-enter,
.transition-bottom-leave-to {
  opacity: 0;
  margin-bottom: calc(var(--unit-xxl) * -1);
}

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

.transition-top-enter,
.transition-top-leave-to {
  opacity: 0;
}

.transition-top-enter .pophover,
.transition-top-leave-to .pophover {
  margin-top: calc(var(--unit-xxl) * -1);
}