/* 全体スタイル */
html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  margin: 0;
  padding: 0;
  color: #2d3748;
  background-color: #f7fafc;
  line-height: 1.6;
}

/* ヘッダー / ヒーローエリア */
.hero {
  background: linear-gradient(135deg, #1a202c 0%, #2d3748 100%);
  color: #fff;
  text-align: center;
  padding: 60px 20px 40px;
}

.hero h1 {
  font-size: 2.5rem;
  margin: 0 0 10px;
  letter-spacing: -0.5px;
}

.subtitle {
  font-size: 1.1rem;
  margin-top: 0;
  opacity: 0.85;
}

.nav-links {
  margin-top: 20px;
  display: flex;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  padding: 10px 20px;
  background: #3182ce;
  color: #fff;
  text-decoration: none;
  border-radius: 8px;
  font-weight: 600;
  transition: background-color 0.2s ease, transform 0.2s ease;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.btn:hover {
  background: #2b6cb0;
  transform: translateY(-1px);
}

.btn-secondary {
  background: #4a5568;
}

.btn-secondary:hover {
  background: #374151;
}

/* メインコンテンツセクション */
.section {
  padding: 40px 20px;
  max-width: 900px;
  margin: auto;
}

/* 目次 (Table of Contents) */
.toc-container {
  background: #ffffff;
  border: 1px solid #e2e8f0;
  border-radius: 12px;
  padding: 24px;
  margin-bottom: 40px;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
}

.toc-container h2 {
  font-size: 1.25rem;
  margin-top: 0;
  margin-bottom: 16px;
  color: #2d3748;
  border-bottom: 2px solid #3182ce;
  padding-bottom: 8px;
}

.toc-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 10px 20px;
}

.toc-list li a {
  color: #3182ce;
  text-decoration: none;
  font-size: 0.95rem;
  display: flex;
  align-items: center;
  padding: 6px 8px;
  border-radius: 6px;
  transition: background-color 0.2s;
}

.toc-list li a:hover {
  background-color: #ebf8ff;
  color: #2b6cb0;
  text-decoration: underline;
}

/* マニュアル項目カード */
.manual-item {
  background: #ffffff;
  border-radius: 12px;
  padding: 28px;
  margin-bottom: 36px;
  border: 1px solid #e2e8f0;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
  scroll-margin-top: 20px;
}

.manual-item h2 {
  font-size: 1.5rem;
  color: #1a202c;
  margin-top: 0;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.manual-item-num {
  background: #3182ce;
  color: #fff;
  font-size: 0.9rem;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.manual-desc {
  color: #4a5568;
  margin-bottom: 16px;
  font-size: 1rem;
}

.manual-list {
  color: #4a5568;
  margin: 0 0 20px 0;
  padding-left: 24px;
  font-size: 1rem;
}

.manual-list li {
  margin-bottom: 8px;
  line-height: 1.6;
}

.manual-list li::marker {
  color: #3182ce;
  font-weight: bold;
}

/* 画像ギャラリー・グリッド */
.image-group {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
  margin-top: 16px;
}

.image-card {
  background: #f7fafc;
  border: 1px solid #edf2f7;
  border-radius: 8px;
  overflow: hidden;
  text-align: center;
  padding: 12px;
}

.image-card img {
  max-width: 100%;
  max-height: 480px;
  height: auto;
  border-radius: 6px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
  transition: transform 0.2s ease;
}

.image-card img:hover {
  transform: scale(1.02);
}

.image-caption {
  font-size: 0.875rem;
  color: #718096;
  margin-top: 10px;
  font-weight: 500;
}

/* 汎用画像スタイル */
img {
  max-width: 100%;
  height: auto;
  display: block;
  margin: 0 auto;
}

/* フッター */
footer {
  background: #1a202c;
  color: #a0aec0;
  text-align: center;
  padding: 30px 20px;
  margin-top: 60px;
}

footer p {
  margin: 6px 0;
}

footer a {
  color: #63b3ed;
  text-decoration: none;
}

footer a:hover {
  text-decoration: underline;
}

.footer-nav {
  margin-bottom: 12px;
}

.footer-nav a {
  margin: 0 10px;
}