body {
    padding-top: 80px;
}

details.gp-custom-details >summary {
  list-style: none;
}
.gp-custom-details > summary::-webkit-details-marker {
  display: none
}

details.gp-custom-details > summary::after {
  margin-left: 1ch;
  display: inline-block;
  transition: 0.22s;
  content: '▶';
}
details.gp-custom-details[open] summary:after {
  transform: rotate(90deg);
}