/* Resource book pages */
.book-body { background: var(--white); padding: clamp(2rem,4vw,3.5rem) 0 clamp(3rem,6vw,5rem); }
.book-body .s-inner { padding-left: var(--pad); padding-right: var(--pad); }
.book-layout { display: grid; grid-template-columns: 300px 1fr; gap: clamp(2rem,5vw,4.5rem); align-items: start; }
.book-nav { position: sticky; top: 86px; }
.book-nav-title { font-size: 0.72rem; font-weight: 600; letter-spacing: 0.12em; text-transform: uppercase; color: var(--soft); margin-bottom: 1.25rem; }
.book-nav ul { list-style: none; margin: 0; padding: 0; }
.book-nav li { border-top: 1px solid var(--rule); }
.book-nav li:first-child { border-top: none; }
.book-nav a { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding: 0.95rem 0; font-size: 0.95rem; line-height: 1.35; color: var(--mid); text-decoration: none; transition: color 0.2s; }
.book-nav a:hover { color: var(--ink); }
.book-nav .arrow { color: var(--soft); flex-shrink: 0; font-size: 1rem; }
.book-nav li.active { position: relative; }
.book-nav li.active a { color: var(--blue); font-weight: 500; }
.book-nav li.active .arrow { visibility: hidden; }
.book-nav li.active::before { content: ""; position: absolute; left: -1.25rem; top: 0; bottom: 0; width: 2px; background: var(--blue); }
.book-content { border-left: 1px solid var(--rule); padding-left: clamp(2rem,5vw,4.5rem); }
.book-content > h1 { font-family: var(--serif); font-size: clamp(2.4rem,5vw,4rem); font-weight: 400; line-height: 1.08; letter-spacing: -0.02em; color: var(--ink); margin: 0 0 2rem; max-width: none; }
.book-content .prose { max-width: 720px; }

@media (max-width: 768px) {
  .book-layout { grid-template-columns: 1fr; gap: 2rem; }
  .book-nav { position: static; }
  .book-nav li.active::before { left: -0.75rem; }
  .book-content { border-left: none; padding-left: 0; }
}