/* ── 活動成果主區塊 */
.er-section { padding: 3rem 0 4rem; }
.er-section-heading {
  font-size: 1.5rem; font-weight: 700; color: var(--c-text);
  margin-bottom: 2.5rem; padding-bottom: .75rem;
  border-bottom: 3px solid var(--c-secondary-lt); display: inline-block;
}

/* ── 時間軸 */
.timeline { list-style: none; padding: 0; margin: 0; }
.timeline-group {
  display: grid; grid-template-columns: 140px 1fr; gap: 0 2rem; margin-bottom: 2.5rem;
}
@media (max-width: 575.98px) {
  .timeline-group { grid-template-columns: 1fr; gap: .75rem; }
}

.timeline-month { text-align: center; padding-top: .2rem; }
.timeline-month-label {
  display: inline-flex; flex-direction: column; align-items: center; justify-content: center;
  width: 120px; min-height: 80px; padding: .75rem 1rem;
  background: var(--c-primary); color: #fff;
  border-radius: var(--radius-md); font-weight: 700; line-height: 1.3; font-size: 1.05rem;
  position: sticky; top: 80px;
}
@media (max-width: 575.98px) {
  .timeline-month-label {
    position: static; width: auto; flex-direction: row;
    gap: .5rem; min-height: unset; padding: .5rem 1rem;
  }
}

/* ── 活動項目 */
.er-items { display: flex; flex-direction: column; gap: .75rem; }
.er-item {
  background: var(--c-white); border-radius: var(--radius-md); box-shadow: var(--shadow-sm);
  overflow: hidden; border: 1px solid var(--c-border); transition: box-shadow var(--trans);
}
.er-item:hover { box-shadow: var(--shadow-md); }

.er-item-link {
  display: flex; align-items: center; gap: 1rem;
  padding: 1rem 1.25rem;
  color: var(--c-text); text-decoration: none; font-weight: 600;
  border-radius: var(--radius-md);
  transition: background var(--trans);
}
.er-item-link:hover { background: var(--c-bg); color: var(--c-text); text-decoration: none; }
.er-item-link:focus-visible { outline: 3px solid var(--c-focus); outline-offset: -2px; }

.er-item-icon {
  flex-shrink: 0; width: 40px; height: 40px; border-radius: 50%;
  background: var(--c-accent); color: var(--c-primary);
  display: flex; align-items: center; justify-content: center; font-size: 1rem;
}
.er-item-title { flex: 1; }

.er-badge-video {
  display: inline-flex; align-items: center; gap: .3rem;
  font-size: .75rem; font-weight: 700; padding: .2rem .6rem;
  background: #e8f0fe; color: #1a56cc;
  border-radius: var(--radius-pill); white-space: nowrap; flex-shrink: 0;
}

.er-item-arrow {
  font-size: .85rem; color: var(--c-muted); flex-shrink: 0;
  transition: transform .2s ease, color .2s ease;
}
.er-item-link:hover .er-item-arrow {
  transform: translateX(3px); color: var(--c-primary);
}