/* book-nav.css — shared navigation component for online books
   Sepia defaults match the vgr twitter book aesthetic.
   Override --nav-* vars in :root to theme for a specific site.
   ---------------------------------------------------------------- */

:root {
  --nav-bg:           #f5f0e8;
  --nav-border:       #d9d0c4;
  --nav-fg:           #5a4e42;
  --nav-label:        #3a3330;
  --nav-arrow:        #8a7e72;
  --nav-hover:        #6b4c2a;
  --nav-max-width:    800px;
  --nav-outer-offset: 432px;
}

/* ── Inline book-nav bar ───────────────────────────────────────── */

.book-nav {
  max-width: var(--nav-max-width);
  margin: 0.75rem auto;
  display: flex;
  gap: 0.5rem;
  align-items: center;
  font-size: 0.8rem;
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--nav-border);
  border-radius: 6px;
  background: var(--nav-bg);
}

.book-nav .nav-left,
.book-nav .nav-center,
.book-nav .nav-right {
  flex: 1;
  min-width: 0;
}
.book-nav .nav-left   { text-align: left; }
.book-nav .nav-center { text-align: center; }
.book-nav .nav-right  { text-align: right; }

.nav-link {
  text-decoration: none;
  color: var(--nav-fg);
  white-space: nowrap;
  display: inline-flex;
  align-items: center;
  max-width: 100%;
}
.nav-link .nav-label {
  overflow: hidden;
  text-overflow: ellipsis;
  font-weight: 600;
  color: var(--nav-label);
}
.nav-link .nav-arrow {
  flex-shrink: 0;
  font-size: 1.1em;
  font-weight: 700;
  color: var(--nav-arrow);
}
.nav-prev .nav-arrow { margin-right: 0.4em; }
.nav-next .nav-arrow { margin-left:  0.4em; }

.nav-link.nav-toc {
  font-weight: 600;
  color: var(--nav-fg);
  font-size: 0.85em;
  letter-spacing: 0.02em;
}
.nav-link:hover                { text-decoration: underline; color: var(--nav-hover); }
.nav-link:hover .nav-label     { color: var(--nav-hover); }
.nav-link:hover .nav-arrow     { color: var(--nav-hover); }
.nav-link.disabled {
  opacity: 0.3;
  pointer-events: none;
  cursor: default;
}

/* ── Floating side navigation ─────────────────────────────────── */

.float-nav,
.float-nav-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  width: 3rem;
  height: 3.2rem;
  text-decoration: none;
  font-family: system-ui, -apple-system, sans-serif;
  color: var(--nav-fg);
  background: var(--nav-bg);
  border: 1px solid var(--nav-border);
  border-radius: 6px;
  opacity: 0.65;
  transition: opacity 0.2s, color 0.15s, box-shadow 0.15s;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
  cursor: pointer;
}
.float-nav:hover,
.float-nav-btn:hover {
  opacity: 1;
  color: var(--nav-hover);
  box-shadow: 0 1px 6px rgba(60,40,20,0.15);
}
.float-nav-chevron {
  font-size: 1.5rem;
  line-height: 1;
  font-weight: 300;
}
.float-nav-label {
  font-size: 0.55rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  margin-top: 0.1rem;
}

/* Prev button: fixed left, vertically centered */
.float-nav-prev {
  position: fixed;
  z-index: 100;
  top: 50%;
  transform: translateY(-50%);
  right: calc(50% + var(--nav-outer-offset) + 0.5rem);
}

/* Right cluster: ToC stacked above Next */
.float-nav-right {
  position: fixed;
  z-index: 100;
  top: 50%;
  transform: translateY(-50%);
  left: calc(50% + var(--nav-outer-offset) + 0.5rem);
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.float-nav-toc { height: 2.6rem; }
.float-nav-toc .float-nav-chevron { font-size: 1.2rem; }

/* Hide float nav on screens where they'd overlap content */
@media (max-width: 900px) {
  .float-nav-prev,
  .float-nav-right { display: none; }
}