body {
  font-family: "Helvetica Neue", Arial, sans-serif;
  line-height: 1.8;
  margin: 0;
  padding: 0 1rem;
  background-color: #f9f9f9;
  color: #333;
}

header {
  background-color: #70b3ff;
  color: white;
  padding: 1.5rem;
  text-align: center;
  border-radius: 0 0 10px 10px;
}

h1, h2, h3 {
  color: #2b4a6e;
}

main {
  max-width: 800px;
  margin: 2rem auto;
  background: white;
  padding: 2rem;
  border-radius: 10px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.05);
}

section {
  margin-bottom: 2.5rem;
}

ul {
  padding-left: 1.5rem;
  margin-top: 1rem;
}

ul li {
  margin-bottom: 0.5rem;
}

.speaker {
  font-weight: bold;
  color: #3a3a3a;
}

.link-button {
  display: inline-block;
  margin-top: 1rem;
  background-color: #70b3ff;
  color: white;
  padding: 0.6rem 1.2rem;
  border-radius: 6px;
  text-decoration: none;
  font-weight: bold;
  transition: background-color 0.3s ease;
}

.link-button:hover {
  background-color: #559de0;
}

/* 共有ボタンスタイル */
.share-buttons {
  margin-top: 20px;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
}

.share-buttons a,
.share-buttons button {
  background-color: #ffe4e8;
  color: #333;
  text-decoration: none;
  padding: 10px 16px;
  border-radius: 9999px;
  font-size: 0.95em;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  border: none;
  cursor: pointer;
  transition: background-color 0.3s, transform 0.2s;
  font-weight: bold;
}

.share-buttons a:hover,
.share-buttons button:hover {
  background-color: #ffd0da;
  transform: scale(1.05);
}

.share-buttons i {
  font-size: 1em;
}

/* 戻るボタン */
.back-to-blog {
  margin-top: 40px;
  text-align: center;
}

.back-to-blog a {
  display: inline-block;
  background-color: #e75480;
  color: #fff;
  padding: 12px 24px;
  border-radius: 9999px;
  text-decoration: none;
  font-weight: bold;
  transition: background-color 0.3s ease;
}

.back-to-blog a:hover {
  background-color: #d74470;
}

/* レスポンシブ対応 */
@media screen and (max-width: 600px) {
  body {
    padding: 0.5rem;
  }

  main {
    padding: 1.5rem;
  }

  h1 {
    font-size: 1.5em;
  }

  .link-button,
  .share-buttons a,
  .share-buttons button,
  .back-to-blog a {
    font-size: 0.9em;
    padding: 10px 14px;
  }
}