details[open] summary ~ * {
  animation: open 0.3s ease-in-out;
}

@keyframes open {
  0% {
    opacity: 0;
  }
  100% {
    opacity: 1;
  }
}
details summary::-webkit-details-marker {
  display: none;
}

details summary {
  width: 100%;
  padding-left: 2rem;
  position: relative;
  cursor: pointer;
  list-style: none;
}

details summary:before {
  content: "+";
  color: var(--blue);
  position: absolute;
  font-size: 1.75rem;
  line-height: 0.3;
  margin-top: 0.75rem;
  left: 0;
  transition: 200ms linear;
}
details[open] summary:before {
  transform: rotate(45deg);
  font-size: 2rem;
}