.timeline-button {
  position: absolute;
  left: -0.375rem;

  width: 0.75rem;
  height: 0.75rem;

  border-radius: 9999px;

  background: #d1d5db;

  display: flex;
  align-items: center;
  justify-content: center;

  font-size: 10px;
  line-height: 1;

  transition: all 0.2s ease;
}

/* hover only when expanded */
.timeline-button:hover:not(.collapsed) {
  background: #6b7280;
}

/* collapsed state */
.timeline-button.collapsed {
  background: transparent !important;
  color: #6b7280;
}