/* 既存の .chapter-icon に上書きで丸枠化 */
.chapter-icon.num-circle{
  width: 26px; height: 26px;
  display: inline-flex; align-items: center; justify-content: center;
  border: 1px solid currentColor; border-radius: 50%;
  font-weight: 700; line-height: 1; font-size: 16px;
}