/* Newsletter archive, grouped into blocks of 5 by issue number. Only
   the block containing the most recent public issue starts open; older
   blocks are collapsed <details> the visitor can click open. */
.newsletter-group {
  margin-bottom: 1rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
  box-shadow: var(--shadow);
  overflow: hidden;
}

.newsletter-group-summary {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.85rem 1.1rem;
  font-weight: 600;
  color: var(--color-primary-dark);
  cursor: pointer;
  list-style: none;
}

.newsletter-group-summary::-webkit-details-marker {
  display: none;
}

.newsletter-group-summary::before {
  content: '▸';
  color: var(--color-accent);
  transition: transform 0.15s ease;
}

.newsletter-group[open] .newsletter-group-summary::before {
  transform: rotate(90deg);
}

.newsletter-group-summary:hover {
  background: var(--color-highlight);
}

.newsletter-group-summary:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: -3px;
}

.newsletter-group .newsletter-list {
  margin: 0;
  padding: 0 1.1rem 1rem;
}

.newsletter-group .newsletter-list li:first-child {
  margin-top: 0.25rem;
}