discourse/app/assets/stylesheets/desktop/post-action-feedback.scss

.post-action-feedback-alert {
  position: absolute;
  top: -1.5rem;
  left: 50%;
  transform: translateX(-50%);
  color: var(--success);
  padding: 0.25rem 0.5rem;
  white-space: nowrap;
  font-size: var(--font-down-2);
  opacity: 1;
  transition: opacity 0.5s ease-in-out;
  z-index: calc(z("timeline") + 1);
  &.-success {
    color: var(--success);
  }

  &.-fail {
    color: var(--danger);
  }

  &.slide-out {
    animation: slide 1s cubic-bezier(0, 0, 0, 2) forwards;
  }
}