quartz-research-note/quartz/components/styles/popover.scss

@keyframes dropin {
  0% {
    opacity: 0;
    visibility: hidden;
  }
  1% {
    opacity: 0;
  }
  100% {
    opacity: 1;
    visibility: visible;
  }
}

.popover {
  z-index: 999;
  position: absolute;
  overflow: visible;
  padding: 1rem;

  & > .popover-inner {
    width: 30rem;
    height: 20rem;
    padding: 0 1rem 1rem 1rem;
    font-weight: initial;
    line-height: initial;
    font-size: initial;
    border: 1px solid var(--gray);
    background-color: var(--light);
    border-radius: 5px;
    box-shadow: 6px 6px 36px 0 rgba(0,0,0,0.25);
    overflow: scroll;
  }

  h1 {
    font-size: 1.5rem;
  }

  visibility: hidden;
  opacity: 0;
  transition: opacity 0.3s ease, visibility 0.3s ease;

  @media all and (max-width: 600px) {
    display: none !important;
  }
}

a:hover .popover, .popover:hover {
  animation: dropin 0.3s ease;
  animation-fill-mode: forwards;
  animation-delay: 0.2s;
}