/* Visual separation between appended sections */
.book-article + .book-article {
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid rgba(0,0,0,.1);
}

/* Make the sentinel invisible but present in flow */
#book-infinite-sentinel {
  height: 1px;
  width: 100%;
}

/* “More below” hint (white down-arrow in blue circle) */
:root {
  --hint-size: 44px;
  --hint-bg: var(--bs-primary, #0d6efd);
  --hint-shadow: 0 8px 22px rgba(13,110,253,.25);
}

.infinite-hint {
  position: fixed;
  left: 50%;
  bottom: calc(env(safe-area-inset-bottom, 0px) + 24px);
  transform: translateX(-50%);
  width: var(--hint-size);
  height: var(--hint-size);
  border-radius: 50%;
  border: 0;
  background: var(--hint-bg);
  color: #fff;
  display: grid;
  place-items: center;
  box-shadow: var(--hint-shadow);
  cursor: pointer;
  z-index: 1050;
  transition: opacity .25s ease, transform .25s ease, visibility .25s;
  animation: hint-bounce 1.6s ease-in-out infinite;
}

.infinite-hint:is(:hover, :focus-visible) {
  transform: translateX(-50%) translateY(-1px);
  outline: 2px solid rgba(255,255,255,.6);
  outline-offset: 2px;
}

.infinite-hint.is-hidden {
  opacity: 0;
  transform: translateX(-50%) translateY(8px);
  visibility: hidden;
  pointer-events: none;
  animation: none;
}

@keyframes hint-bounce {
  0%, 100% { transform: translateX(-50%) translateY(0); }
  50%      { transform: translateX(-50%) translateY(-6px); }
}