/* ══════════════════════════════════════════════════════════════
   Favorite (heart) buttons — shared across book cards, book detail,
   audiobook list/player, and the dedicated Favorites page.
══════════════════════════════════════════════════════════════ */
.fav-btn {
  display: inline-flex; align-items: center; justify-content: center;
  border: none; cursor: pointer; padding: 0;
  background: rgba(255,255,255,.9); color: var(--ds-text-subtle, #626a75);
  border-radius: 50%; transition: transform .15s ease, color .15s ease, background-color .15s ease;
}
.fav-btn:hover { transform: scale(1.08); color: #D16655; }
.fav-btn:focus-visible { outline: 3px solid var(--ds-focus-ring, #a74234); outline-offset: 2px; }
.fav-btn.is-favorited { color: #D16655; }
.fav-btn.fav-btn--pulse { animation: fav-pulse .35s ease; }
@keyframes fav-pulse {
  0% { transform: scale(1); }
  40% { transform: scale(1.3); }
  100% { transform: scale(1); }
}

/* Small overlay variant — sits on top of book/audiobook cover thumbnails */
.book-card { position: relative; }
.fav-btn--card {
  position: absolute; top: 8px; inset-inline-start: 8px; z-index: 5;
  width: 32px; height: 32px; font-size: .95rem;
  box-shadow: 0 2px 8px rgba(0,0,0,.15);
}
[data-theme="dark"] .fav-btn--card { background: rgba(15,25,35,.75); color: #a9bdcc; }

/* Larger standalone variant — book detail / audiobook player */
.fav-btn--lg {
  width: 46px; height: 46px; font-size: 1.15rem;
  background: var(--ds-surface, #fff); border: 1.5px solid var(--ds-border-light, #f0ece6);
  box-shadow: var(--ds-shadow-sm, 0 1px 3px rgba(0,0,0,.06));
}

/* Dark hero variant — audiobook player's dark navy header */
.fav-btn--on-dark {
  width: 46px; height: 46px; font-size: 1.15rem;
  background: rgba(255,255,255,.12); color: rgba(255,255,255,.85);
  backdrop-filter: blur(4px);
}
.fav-btn--on-dark:hover { color: #ef8f80; }
.fav-btn--on-dark.is-favorited { color: #ef8f80; }