/* === 1. サムネイル表示（中央寄せ・レスポンシブ） === */
.pdf-preview-thumbnails {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  justify-items: center;
}
@media screen and (min-width: 768px) {
  .pdf-preview-thumbnails {
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
  }
}

/* === 2. サムネイル画像 === */
.pdf-thumb img {
  width: 100%;
  max-width: 240px;
  height: auto;
  border-radius: 8px;
  cursor: pointer;
  box-shadow: 0 4px 10px rgba(0,0,0,0.1);
  transition: transform 0.3s ease;
}
.pdf-thumb img:hover {
  transform: scale(1.05);
}

/* === 3. PDFモーダル === */
.modal {
  display: none;
  position: fixed;
  z-index: 9999;
  top: 0; left: 0;
  width: 100vw;
  height: 100vh;
  background-color: rgba(0, 0, 0, 0.9);
  justify-content: center;
  align-items: center;
}
.modal iframe {
  width: 90vw;
  height: 90vh;
  background-color: white;
  border: none;
  border-radius: 8px;
}
.modal-close {
  position: absolute;
  top: 20px;
  right: 30px;
  font-size: 3rem;
  color: white;
  cursor: pointer;
  z-index: 10000;
}

/* === 4. レイアウト：画像左・テキスト右（PC） / 中央寄せ（SP） === */
.book-section__flex {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 40px;
  max-width: 1080px;
  margin: 200px auto;
  padding: 100px 20px 0;
}
.book-section__img,
.book-section__text {
  width: 100%;
}
.book-section__img img {
  width: 100%;
  max-width: 360px;
  height: auto;
  display: block;
  margin: 0 auto;
}
.book-section__text {
  text-align: left;
  line-height: 1.8;
}
@media screen and (min-width: 768px) {
  .book-section__flex {
    flex-direction: row;
    justify-content: space-between;
    align-items: flex-start;
  }
  .book-section__img {
    flex: 1;
    max-width: 40%;
  }
  .book-section__text {
    flex: 1;
    max-width: 60%;
    padding-left: 40px;
  }
}

/* === 5. テキスト調整 === */
.book-section__title,
.book-section__subtitle,
.book-section__description {
  word-break: break-word;
  line-height: 1.8;
  margin-bottom: 1em;
}
.book-section__title {
  font-size: 1.6em;
  font-weight: bold;
}
.book-section__subtitle {
  font-size: 1.2em;
  color: #666;
}

/* === 6. セクション間余白調整 === */
.visual__book {
  margin-bottom: 20px;
  height: 600px;
}
.wrapper {
  margin-bottom: 100px;
}

/* === 7. ボタン余白調整 === */
.btn__index.mt-30 {
  margin-top: 30px;
}
.btn__icon--arrow-right {
  margin-top: 0;
}