.side-note {
  position: sticky;
  top: 28px;
  padding-top: 8px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-family: "Hiragino Sans GB", "PingFang SC", "Microsoft YaHei", sans-serif;
  font-size: 13px;
  line-height: 1.7;
}

.side-note strong {
  display: block;
  margin-bottom: 8px;
  color: var(--ink);
  font-size: 15px;
}

.directory {
  display: grid;
  gap: 9px;
}

.directory a {
  display: block;
  padding-left: 10px;
  border-left: 2px solid transparent;
  color: var(--muted);
  line-height: 1.55;
  transition: color 180ms ease, border-color 180ms ease;
}

.directory a:hover {
  color: var(--accent);
  border-left-color: var(--accent);
}

.directory a[aria-current="page"] {
  color: var(--ink);
  border-left-color: var(--green);
  font-weight: 700;
}

@media (max-width: 820px) {
  .side-note {
    position: static;
    order: 3;
    margin-top: 52px;
  }
}

@media print {
  .side-note {
    display: none;
  }
}