.post-content {
    border-right: 1px solid #cfcfcf;
    border-left: 1px solid #cfcfcf;
    padding-right: 20px;
    padding-left: 20px;
    font-family: 'noto-sans-jp', sans-serif;
    line-height: 1.6;
  }

.breadcrumb {
    font-size: 14px;
    color: #666;
  }
  .breadcrumb a {
    text-decoration: none;
    color: #0073aa;
  }
  .breadcrumb a:hover {
    text-decoration: underline;
  }

  .single-footer {
    text-align: center;  /* 子要素を中央寄せ */
    margin-top: 2rem;    /* ページ本文との間隔 */
  }

  h2 {
    font-weight: bold;
    position: relative;
    padding: 0.5em 1em;
    background: #f0f8ff;   /* 薄い水色 */
    padding-left: 5px solid 10px;  /* 左に余白を追加 */
    border-left: 4px solid #0073aa;  /* 左線を追加 */
    margin-top: 2em;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
  }

  h3 {
    /* padding-top: 50px;
    padding-bottom: 20px; */
    position: relative;
    padding-bottom: 0.3em;
    border-bottom: 2px solid #0073aa;
    font-weight: bold;
    margin-top: 1.5em;
  }

  h4 {
    position: relative;
    padding-left: 1.2em;
    font-weight: bold;
    margin-top: 1em;
  }
  h4::before {
    content: "★";
    position: absolute;
    left: 0;
    color: #0073aa;
  }

  h5 {
    padding-top: 30px;
    padding-bottom: 10px;
  }

  .footer-inner {
    display: flex;
    flex-direction: column;
    gap: 2rem;
    width: 100%;
    max-width: 1140px; /* Bootstrapなどと揃える */
    margin: 0 auto;
    padding-left: 15px;
    padding-right: 15px;
  }

  .share-buttons {
    display: flex;
    gap: 10px;
    justify-content: center;
  }

  .related-posts {
    width: 100%;
  }

  .related-posts h2 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
  }

  .related-posts-list {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    list-style: none;
    padding: 0;
    margin: 0;
  }

  .related-posts-list li {
    width: calc(33.333% - 13.333px);
  }

  .related-posts-list .thumbnail img {
    width: 100%;
    height: auto;
    border-radius: 6px;
  }

  .related-posts-list .title {
    margin-top: 8px;
    font-weight: bold;
    line-height: 1.4;
  }

  .post-meta-box {
    background: #eaf7fc;
    border-radius: 6px;
    padding: 1rem;
    margin-top: 2rem;
    font-size: 0.9rem;
  }
  .post-meta-box table {
    width: 100%;
    border-collapse: collapse;
  }
  .post-meta-box th {
    text-align: left;
    width: 25%;
    padding-right: 0.5rem;
    color: #0073aa;
  }
  .post-meta-box td {
    padding-bottom: 0.5rem;
  }