/* 書本容器、翻頁 3D 機制、開場覆蓋層、固定元件 */

#fx-canvas {
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 5;
}

/* ---------- 開場覆蓋層（書封面：深鼠尾草綠布面＋燙金） ---------- */

.intro {
  position: fixed;
  inset: 0;
  z-index: 40;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  background: var(--sage);
  cursor: pointer;
  transform-origin: left center;
  transform: rotateY(0deg);
  transition: transform 0.9s cubic-bezier(0.2, 0.7, 0.2, 1);
  transform-style: preserve-3d;
  backface-visibility: hidden;
}

.intro::after {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--gold-soft);
  transform: rotateY(180deg);
  backface-visibility: hidden;
  box-shadow: inset 0 0 40px rgba(36, 49, 43, 0.35);
}

.intro.opened {
  transform: rotateY(-178deg);
  box-shadow: 40px 0 60px var(--shadow);
}

.intro-texture {
  position: absolute;
  inset: 0;
  background-image:
    repeating-linear-gradient(0deg, rgba(255, 255, 255, 0.06) 0 1px, transparent 1px 7px),
    repeating-linear-gradient(90deg, rgba(255, 255, 255, 0.04) 0 1px, transparent 1px 9px);
}

.intro-frame {
  position: absolute;
  inset: 16px;
  border: 1px solid var(--gold);
  opacity: 0.85;
}

.intro-frame::before {
  content: '';
  position: absolute;
  inset: 6px;
  border: 1px solid var(--gold);
  opacity: 0.6;
  background-image:
    radial-gradient(circle, var(--gold) 2px, transparent 2.5px),
    radial-gradient(circle, var(--gold) 2px, transparent 2.5px),
    radial-gradient(circle, var(--gold) 2px, transparent 2.5px),
    radial-gradient(circle, var(--gold) 2px, transparent 2.5px);
  background-size: 6px 6px;
  background-position: top 0 left 0, top 0 right 0, bottom 0 left 0, bottom 0 right 0;
  background-repeat: no-repeat;
}

.intro-glow {
  position: absolute;
  width: min(80vw, 360px);
  aspect-ratio: 1;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(166, 132, 86, 0.45), transparent 70%);
  opacity: 0;
  animation: glow-rise 1.4s var(--ease-out) 0.2s both;
  filter: blur(2px);
}

.intro-wreath {
  position: relative;
  width: min(62vw, 260px);
  aspect-ratio: 1;
  opacity: 0;
  transform: scale(0.9);
  animation: wreath-reveal 0.9s var(--ease-out) 0.15s both;
}

.intro-wreath img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.intro-names {
  position: relative;
  font-family: var(--font-en);
  font-style: italic;
  font-weight: 600;
  font-size: clamp(1.7rem, 7.5vw, 2.3rem);
  background: linear-gradient(100deg, #b8925a, #f3e2b8 45%, #a68456 60%, #e9d3a0);
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  color: var(--gold-soft);
  opacity: 0;
  overflow: hidden;
  transform: translateY(10px);
  animation: fade-up 0.8s var(--ease-out) 0.7s both;
}

.intro-names::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(100deg, transparent 0%, rgba(255, 255, 255, 0.85) 45%, transparent 60%);
  transform: translateX(-130%);
  animation: sweep 1.1s ease-out 1.5s both;
  mix-blend-mode: screen;
}

.intro-amp {
  font-family: var(--font-en);
  font-style: italic;
  margin: 0 0.3em;
}

.intro-date {
  position: relative;
  font-family: var(--font-en);
  font-size: 1.1rem;
  letter-spacing: 0.08em;
  font-variant-numeric: lining-nums;
  color: var(--gold-soft);
  opacity: 0;
  transform: translateY(10px);
  animation: fade-up 0.7s var(--ease-out) 1.1s both;
}

.intro-hint {
  position: relative;
  margin-top: 1.4rem;
  font-size: 1rem;
  color: var(--gold);
  letter-spacing: 0.1em;
  opacity: 0;
  transform: translateY(10px);
  animation: fade-up 0.6s var(--ease-out) 1.4s both, breathe 2.2s ease-in-out 2s infinite;
}

@keyframes wreath-reveal {
  from { opacity: 0; transform: scale(0.9); }
  to { opacity: 1; transform: scale(1); }
}

@keyframes glow-rise {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes sweep {
  from { transform: translateX(-130%); }
  to { transform: translateX(130%); }
}

@keyframes fade-up {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes breathe {
  0%, 100% { opacity: 0.55; }
  50% { opacity: 1; }
}

@media (prefers-reduced-motion: reduce) {
  .intro { transition: opacity 0.2s linear; }
  .intro.opened { transform: none; opacity: 0; pointer-events: none; }
  .intro-glow, .intro-wreath, .intro-names, .intro-date, .intro-hint, .intro-names::after {
    animation: none !important;
    opacity: 1;
    transform: none;
  }
  .intro-names::after { display: none; }
}

/* ---------- 書本 ---------- */

.book {
  position: relative;
  z-index: 6;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: env(safe-area-inset-top, 0) 0 env(safe-area-inset-bottom, 0);
}

.pages {
  position: relative;
  width: min(92vw, 420px);
  height: min(72dvh, 680px);
  max-height: calc(100dvh - var(--nav-fab-row-h) - var(--nav-main-row-h) - 3rem);
  perspective: 2400px;
}

.book.no-motion .sheet {
  transition: none;
}

.sheet {
  position: absolute;
  inset: 0;
  transform-style: preserve-3d;
  transform-origin: left center;
  transform: rotateY(0deg);
  transition: transform 0.7s var(--ease-out);
  border-radius: var(--radius-page);
}

.sheet.is-left {
  transform: rotateY(-178deg);
}

.sheet.is-far {
  visibility: hidden;
}

.face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  border-radius: inherit;
  background: var(--paper);
  box-shadow: 0 18px 40px var(--shadow), 0 2px 6px rgba(36, 49, 43, 0.15);
  overflow-y: auto;
  overscroll-behavior: contain;
  -webkit-overflow-scrolling: touch;
}

.face-front {
  background-image: url('/assets/img/paper.webp');
  background-size: 420px;
  background-blend-mode: multiply;
}

.face-back {
  transform: rotateY(180deg);
  background: var(--gold-soft);
  background-image: url('/assets/img/paper.webp');
  background-size: 420px;
  background-blend-mode: multiply;
  overflow: hidden;
}

@media (prefers-reduced-motion: reduce) {
  .sheet {
    transition: opacity 0.2s linear;
    transform: none !important;
  }
  .sheet:not(.is-current) {
    opacity: 0;
    pointer-events: none;
  }
  .sheet.is-current {
    opacity: 1;
  }
}

/* ---------- 底部導覽 ---------- */

.book-nav {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.3rem;
  margin-top: 0.6rem;
  padding: 0.2rem max(0.6rem, env(safe-area-inset-right, 0px)) calc(env(safe-area-inset-bottom, 0px) + 1.2rem) max(0.6rem, env(safe-area-inset-left, 0px));
  background: linear-gradient(to top, rgba(250, 248, 243, 0.85), rgba(250, 248, 243, 0));
}

.book-nav-fab-row {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: var(--nav-fab-row-h);
}

.book-nav-main {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  min-height: var(--nav-main-row-h);
}

.btn-nav {
  width: var(--touch);
  height: var(--touch);
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  color: var(--sage);
  background: rgba(250, 248, 243, 0.7);
}

.btn-nav:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.dots {
  display: flex;
  list-style: none;
  margin: 0;
  padding: 0;
  gap: 0.2rem;
}

.dots li {
  position: relative;
}

.dots button {
  width: var(--touch);
  height: var(--touch);
  display: flex;
  align-items: center;
  justify-content: center;
}

.dots button::before {
  content: '';
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--gold-soft);
  transition: transform 0.2s;
}

.dots button[aria-current="page"]::before {
  background: var(--gold);
  transform: scale(1.6);
}

.dots button[aria-current="page"]::after {
  content: attr(aria-label);
  position: absolute;
  top: calc(100% - 0.35rem);
  left: 50%;
  transform: translateX(-50%);
  font-size: 0.8rem;
  line-height: 1.2;
  color: var(--sage);
  white-space: nowrap;
  pointer-events: none;
}

/* 內容可捲時，卡片底部的紙色漸層提示；捲到底淡出 */
.face-front::after {
  content: '';
  display: block;
  position: sticky;
  bottom: 0;
  height: 28px;
  margin-top: -28px;
  background: linear-gradient(to top, var(--paper), rgba(250, 248, 243, 0));
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.2s linear;
}

.face-front.can-scroll:not(.at-end)::after {
  opacity: 1;
}

.face-front.cover-back::after {
  display: none;
}

/* ---------- 固定元件 ---------- */

.music-toggle {
  position: fixed;
  top: calc(env(safe-area-inset-top, 0px) + 0.8rem);
  right: 0.8rem;
  z-index: 30;
  width: var(--touch);
  height: var(--touch);
  border-radius: 50%;
  background: var(--paper);
  color: var(--gold);
  box-shadow: 0 4px 12px var(--shadow);
  display: flex;
  align-items: center;
  justify-content: center;
}

.toast {
  position: fixed;
  top: calc(env(safe-area-inset-top, 0px) + 0.8rem + var(--touch) + 0.5rem);
  right: 0.8rem;
  z-index: 30;
  max-width: min(18rem, calc(100vw - 1.6rem));
  padding: 0.6rem 0.9rem;
  border: 1px solid var(--gold);
  border-radius: 12px;
  background: var(--paper);
  color: var(--ink);
  font-size: 1rem;
  line-height: 1.5;
  box-shadow: 0 4px 12px var(--shadow);
  opacity: 0;
  transition: opacity 0.4s ease;
  pointer-events: none;
}

.toast.show {
  opacity: 1;
}

.toast[hidden] {
  display: none;
}

.copy-buffer {
  position: fixed;
  top: 0;
  left: 0;
  width: 1px;
  height: 1px;
  opacity: 0;
  font-size: 16px;
  pointer-events: none;
}

.music-toggle.playing svg {
  animation: disc-spin 3.4s linear infinite;
}

@keyframes disc-spin {
  to { transform: rotate(360deg); }
}

.rsvp-fab {
  position: static;
  padding: 0.55rem 1.1rem;
  min-height: var(--touch);
  border-radius: 999px;
  background: #866639;
  color: var(--paper);
  font-size: 1rem;
  letter-spacing: 0.04em;
  white-space: nowrap;
  box-shadow: 0 6px 16px var(--shadow);
}

.rsvp-fab[hidden] {
  display: none;
}

@media (prefers-reduced-motion: reduce) {
  .dots button::before,
  .face-front::after { transition: none; }
  .music-toggle.playing svg { animation: none; }
  .toast { transition: none; }
}