element-call-Github/src/room/ReactionsOverlay.module.css

.container {
  position: absolute;
  display: inline;
  z-index: 2;
  pointer-events: none;
  width: 100vw;
  height: 100vh;
  left: 0;
  top: 0;
}

.reaction {
  font-size: 32pt;
  /* Reactions are "active" for 3 seconds (as per REACTION_ACTIVE_TIME_MS), give a bit more time for it to fade out. */
  animation-duration: 4s;
  animation-name: reaction-up;
  width: fit-content;
  position: relative;
  top: 80vh;
}

@keyframes reaction-up {
  from {
    opacity: 1;
    translate: 0 0;
    scale: 200%;
    top: 80vh;
  }

  to {
    top: 0;
    opacity: 0;
    scale: 100%;
  }
}

@media (prefers-reduced-motion) {
  @keyframes reaction-up-reduced {
    from {
      opacity: 1;
    }

    to {
      opacity: 0;
    }
  }

  .reaction {
    font-size: 48pt;
    animation-name: reaction-up-reduced;
    top: calc(-50vh + (48pt / 2));
    left: calc(50vw - (48pt / 2)) !important;
  }
}