/* ── 1. Tokens ──────────────────────────────────────────────────── */
:root {
  /* background */
  --bg-1: #F4EEE6;
  --bg-2: #EFE5D8;
  --bg-3: #E8D9C8;

  /* paper */
  --paper: #FFFDF7;
  --paper-2: #FAF5EA;
  --paper-deep: #F6ECD9;

  /* text */
  --ink: #4E4038;
  --ink-soft: #66554A;

  /* accent */
  --accent: #9D6B6B;
  --accent-2: #B98585;
  --accent-3: #C8A27A;
  --seal-deep: #7C4E4E;

  /* lines & shadows */
  --line: rgba(78, 64, 56, 0.16);
  --shadow-soft: 0 10px 30px -14px rgba(74, 55, 41, 0.35);
  --shadow-paper: 0 34px 70px -26px rgba(74, 55, 41, 0.42), 0 6px 16px -8px rgba(74, 55, 41, 0.16);

  /* type */
  --font-serif: "Playfair Display", "Georgia", serif;
  --font-hand: "Caveat", "Comic Sans MS", cursive;
  --font-read: "Kalam", "Segoe Print", cursive;

  --noise: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='180' height='180'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='2' stitchTiles='stitch'/><feColorMatrix type='saturate' values='0'/><feComponentTransfer><feFuncA type='linear' slope='0.45'/></feComponentTransfer></filter><rect width='180' height='180' filter='url(%23n)'/></svg>");

  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
  --ease-spring: cubic-bezier(0.34, 1.3, 0.55, 1);
}

/* ── 2. Base ────────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-serif);
  color: var(--ink);
  background: var(--bg-1);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  overflow: hidden;
  height: 100%;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 60;
  pointer-events: none;
  background-image: var(--noise);
  opacity: 0.05;
}

::selection { background: rgba(157, 107, 107, 0.28); }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 3px;
}

img { max-width: 100%; }

.skip-link {
  position: fixed;
  top: -100px;
  left: 16px;
  z-index: 100;
  padding: 10px 16px;
  background: var(--ink);
  color: var(--paper);
  border-radius: 6px;
  text-decoration: none;
  font-size: 0.9rem;
  transition: top 0.25s ease;
}
.skip-link:focus { top: 12px; }

/* ── 2b. Scrollbars ────────────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
  border-radius: 99px;
  border: 1px solid transparent;
  background: transparent;
  background-clip: padding-box;
}
.page:hover::-webkit-scrollbar-thumb,
.page.is-scrolling::-webkit-scrollbar-thumb {
  background: linear-gradient(180deg, var(--accent-2) 0%, var(--accent) 100%);
  background-clip: padding-box;
}
.page:hover::-webkit-scrollbar-thumb:hover {
  background: linear-gradient(180deg, var(--accent) 0%, var(--seal-deep) 100%);
  background-clip: padding-box;
}
::-webkit-scrollbar-corner { background: transparent; }

/* Firefox */
* {
  scrollbar-width: thin;
  scrollbar-color: transparent transparent;
}
.page:hover,
.page.is-scrolling {
  scrollbar-color: var(--accent-2) transparent;
}

/* ── 3. Page system ─────────────────────────────────────────────── */
.page {
  position: fixed;
  inset: 0;
  z-index: 1;
  overflow-y: auto;
  overflow-x: hidden;
  overscroll-behavior: contain;
  -webkit-overflow-scrolling: touch;
  display: flex;
  flex-direction: column;
  text-align: center;
  opacity: 0;
  visibility: hidden;
  transform: translateY(18px);
  filter: blur(8px);
  transition: opacity 0.7s ease, transform 0.7s var(--ease-out), filter 0.7s ease, visibility 0s 0.7s;
}
.page.is-active {
  z-index: 2;
  opacity: 1;
  visibility: visible;
  transform: none;
  filter: none;
  transition-delay: 0s;
}
.page.is-leaving {
  z-index: 3;
  opacity: 0;
  transform: translateY(-14px);
  filter: blur(8px);
  transition-duration: 0.5s, 0.5s, 0.5s, 0s;
  transition-delay: 0s, 0s, 0s, 0.5s;
}

.page-inner {
  margin: auto;
  width: 100%;
  padding: clamp(56px, 10vh, 110px) 16px clamp(72px, 12vh, 110px);
}

/* page backgrounds */
.page-envelope {
  background:
    radial-gradient(130% 90% at 18% -5%, rgba(255, 252, 244, 0.95) 0%, rgba(255, 252, 244, 0) 55%),
    linear-gradient(180deg, var(--bg-1) 0%, var(--bg-2) 55%, var(--bg-3) 100%);
}
.page-envelope::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: radial-gradient(135% 110% at 50% 42%, transparent 52%, rgba(90, 64, 44, 0.18) 100%);
}
.page-envelope::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 5;
  pointer-events: none;
  background: rgba(74, 52, 38, 0.16);
  opacity: 0;
  transition: opacity 0.7s ease;
}
.page-envelope.is-opening::after { opacity: 1; }

.page-letter {
  background: linear-gradient(180deg, var(--bg-2) 0%, var(--bg-1) 50%, var(--bg-2) 100%);
}
.page-letter .page-inner { max-width: 800px; }

.page-memories {
  background: linear-gradient(180deg, var(--bg-2) 0%, var(--bg-3) 60%, var(--bg-2) 100%);
}
.page-memories .page-inner { max-width: 980px; }

/* ── 4. Entrance choreography ──────────────────────────────────── */
.page.is-entering .hero-inner > *,
.page.is-entering .chapter-head,
.page.is-entering .memories-note,
.page.is-entering .btn-continue,
.page.is-entering .stack-nav,
.page.is-entering .stack-count { opacity: 0; }

/* PAGE 1 · envelope */
.page-envelope.is-entering .hero-inner > * { animation: riseIn 0.9s var(--ease-out) both; }
.page-envelope.is-entering .hero-star  { animation-delay: 0.05s; }
.page-envelope.is-entering .hero-title { animation-delay: 0.15s; }
.page-envelope.is-entering .hero-heart { animation-delay: 0.28s; }
.page-envelope.is-entering .envelope   { animation: envIn 1s var(--ease-out) 0.4s both; }
.page-envelope.is-entering .hero-hint  { animation-delay: 0.95s; }
.page-envelope.is-entering .btn-cta    { animation-delay: 1.1s; }
.page-envelope.is-entering .hero-bouquet { animation-delay: 0.35s; }

/* PAGE 2 · letter */
.page-letter.is-entering .chapter-head { animation: riseIn 0.9s var(--ease-out) 0.1s both; }
.page-letter.is-entering .letter-paper {
  opacity: 0;
  transform: rotate(-1.6deg) scale(0.97);
  filter: blur(8px);
  animation: paperIn 1.2s var(--ease-out) 0.15s both;
}
.page-letter.is-entering .btn-continue { animation: riseIn 0.9s var(--ease-out) 1.6s both; }

/* PAGE 3 · memories */
.page-memories.is-entering .chapter-head { animation: riseIn 0.9s var(--ease-out) 0.05s both; }
.page-memories.is-entering .polaroid {
  opacity: 0;
  animation: cardIn 0.95s var(--ease-out) both;
  animation-delay: var(--d, 0s);
}
.page-memories.is-entering .stack-nav { animation: riseIn 0.7s var(--ease-out) 0.5s both; }
.page-memories.is-entering .stack-count { animation: riseIn 0.7s var(--ease-out) 0.62s both; }
.page-memories.is-entering .memories-note { animation: riseIn 0.9s var(--ease-out) 0.85s both; }

.sign-squiggle {
  display: block;
  width: min(220px, 60%);
  height: 18px;
  margin: 4px 0 0;
  color: var(--accent-2);
}
.letter-signature .sign-squiggle {
  stroke-dasharray: 230;
  stroke-dashoffset: 230;
}
.reveal-line.is-visible .sign-squiggle { animation: draw 1.1s var(--ease-out) 0.3s forwards; }

/* ── 5. Fixed chrome: chapter dots, music toggle ────────────────── */
.page-dots {
  position: fixed;
  bottom: max(18px, env(safe-area-inset-bottom));
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 10px;
  z-index: 85;
}
.dot {
  width: 8px;
  height: 8px;
  padding: 0;
  border: 0;
  border-radius: 99px;
  background: rgba(78, 64, 56, 0.3);
  cursor: pointer;
  transition: width 0.35s var(--ease-out), background 0.35s ease, transform 0.3s ease;
}
.dot:hover { transform: scale(1.3); background: rgba(78, 64, 56, 0.5); }
.dot.is-active { width: 24px; background: var(--accent); }

.music-toggle {
  position: fixed;
  top: max(16px, env(safe-area-inset-top));
  right: max(16px, env(safe-area-inset-right));
  z-index: 90;
  width: 46px;
  height: 46px;
  border-radius: 50%;
  border: 1px solid rgba(157, 107, 107, 0.45);
  background: rgba(255, 253, 247, 0.72);
  color: var(--accent);
  font-size: 1.15rem;
  display: grid;
  place-items: center;
  cursor: pointer;
  box-shadow: 0 6px 16px -8px rgba(90, 64, 44, 0.35);
  transition: transform 0.3s ease, background 0.3s ease, color 0.3s ease, box-shadow 0.3s ease;
}
.music-toggle:hover { transform: translateY(-2px); background: var(--paper); }
.music-toggle.is-playing {
  background: var(--accent);
  color: var(--paper);
  border-color: var(--accent);
  box-shadow: 0 8px 20px -8px rgba(157, 107, 107, 0.55);
}
.music-toggle.is-playing i { animation: heartPulse 2.6s ease-in-out infinite; }

/* ── 6. PAGE 1 · hero + envelope ────────────────────────────────── */
.hero-inner { max-width: 600px; }

.hero-bouquet {
  position: absolute;
  left: 3%;
  bottom: 4%;
  width: clamp(84px, 13vw, 148px);
  opacity: 0.85;
  animation: bouquetFloat 5.5s ease-in-out infinite;
  pointer-events: none;
}

.hero-star {
  color: var(--accent-3);
  font-size: clamp(1.1rem, 2.6vw, 1.45rem);
  margin: 0 0 4px;
  animation: twinkle 3.6s ease-in-out infinite;
}

.hero-title {
  font-family: var(--font-serif);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.24em;
  font-size: clamp(1.7rem, 5.6vw, 3.1rem);
  color: var(--ink);
  margin: 0;
  padding-left: 0.24em;
}

.hero-heart {
  color: var(--accent);
  font-size: clamp(1rem, 2.4vw, 1.25rem);
  margin: 14px 0 6px;
  animation: heartPulse 4.5s ease-in-out infinite;
}

.hero-fade { transition: opacity 0.4s ease, transform 0.4s ease; }
.page-envelope.is-opening .hero-fade { opacity: 0; transform: translateY(8px); }

/* ── 7. The envelope itself ────────────────────────────────────── */
.envelope {
  position: relative;
  width: min(480px, 88vw);
  aspect-ratio: 10 / 7;
  margin: 30px auto 16px;
  perspective: 1600px;
  filter: drop-shadow(0 26px 28px rgba(74, 55, 41, 0.3));
  transition: transform 0.7s var(--ease-out);
  will-change: transform;
}
.envelope.is-opening { transform: translateY(-3.5vh) scale(0.985); }

.env-letter {
  position: absolute;
  left: 5%;
  right: 5%;
  top: -14%;
  height: 52%;
  z-index: 3;
  background: linear-gradient(172deg, var(--paper) 0%, #F8F0E1 100%);
  border-radius: 6px;
  box-shadow: 0 4px 14px rgba(90, 64, 44, 0.22);
  padding: clamp(10px, 2.4vw, 16px) clamp(14px, 3vw, 24px);
  transform: translateY(0) rotate(-1.5deg);
  transition: transform 0.85s cubic-bezier(0.3, 0.9, 0.3, 1);
  will-change: transform;
}
.env-letter::after {
  content: "";
  position: absolute;
  left: 8%;
  right: 8%;
  bottom: 20%;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(120, 90, 60, 0.25), transparent);
}
.env-letter p {
  font-family: var(--font-read);
  font-size: clamp(0.6rem, 1.5vw, 0.78rem);
  line-height: 1.55;
  color: var(--ink-soft);
  margin: 0 0 6px;
  text-align: left;
  opacity: 0.9;
}
.env-letter .env-peek-3 { opacity: 0.45; margin: 0; }
.envelope.is-out .env-letter { transform: translateY(-150%) rotate(-0.5deg); }

/* envelope body panels */
.env-back {
  position: absolute;
  inset: 0;
  z-index: 1;
  border-radius: 8px;
  border: 1px solid rgba(140, 110, 80, 0.3);
  background: linear-gradient(160deg, #FBF3E4 0%, #F4E7D2 60%, #EDDCC2 100%);
}
.env-back::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 8px;
  background-image: var(--noise);
  opacity: 0.4;
  mix-blend-mode: multiply;
}
.env-back::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 8px;
  box-shadow: inset 0 0 46px rgba(140, 110, 80, 0.2);
}

.env-side {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 50%;
  z-index: 2;
}
.env-side-left  { left: 0; clip-path: polygon(0 0, 100% 50%, 0 100%); background: linear-gradient(115deg, #F3E5CC 0%, #EAD8BA 100%); }
.env-side-right { right: 0; clip-path: polygon(100% 0, 0 50%, 100% 100%); background: linear-gradient(245deg, #F3E5CC 0%, #EAD8BA 100%); }

.env-bottom {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 50%;
  z-index: 2;
  clip-path: polygon(50% 0, 0 100%, 100% 100%);
  background: linear-gradient(180deg, #F6E9D2 0%, #EEDDC0 100%);
}

/* top flap */
.env-flap {
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 50%;
  z-index: 4;
  transform-origin: top center;
  transform-style: preserve-3d;
  transition: transform 0.75s cubic-bezier(0.6, 0.05, 0.28, 1);
  will-change: transform;
}
.env-flap-front,
.env-flap-inner {
  position: absolute;
  inset: 0;
  clip-path: polygon(0 0, 100% 0, 50% 100%);
  backface-visibility: hidden;
}
.env-flap-front {
  background: linear-gradient(180deg, #FCF3E2 0%, #F1E0C4 100%);
}
.env-flap-front::after {
  content: "";
  position: absolute;
  inset: 0;
  clip-path: polygon(0 0, 100% 0, 50% 100%);
  background-image: var(--noise);
  opacity: 0.35;
  mix-blend-mode: multiply;
}
.env-flap-inner {
  background: linear-gradient(180deg, #EFE0C6 0%, #E2CDAC 100%);
  transform: rotateX(180deg);
}
.envelope.is-open .env-flap { transform: rotateX(180deg); }

/* address + stamp */
.env-address {
  position: absolute;
  left: 50%;
  top: 46%;
  width: 84%;
  transform: translate(-50%, -50%);
  display: flex;
  flex-direction: column;
  gap: 1px;
  z-index: 2;
}
.env-to {
  font-family: var(--font-hand);
  font-weight: 600;
  font-size: clamp(1.05rem, 2.5vw, 1.45rem);
  color: var(--ink);
  line-height: 1.15;
}
.env-from {
  font-family: var(--font-hand);
  font-weight: 500;
  font-size: clamp(0.78rem, 1.8vw, 1rem);
  color: var(--ink-soft);
  line-height: 1.2;
}
.env-stamp {
  position: absolute;
  top: 7%;
  right: 6%;
  width: clamp(42px, 6.4vw, 58px);
  transform: rotate(8deg);
  z-index: 2;
}
.env-stamp img {
  width: 100%;
  display: block;
  filter: drop-shadow(0 3px 4px rgba(90, 64, 44, 0.3));
}

/* wax seal */
.env-seal {
  position: absolute;
  left: 50%;
  top: 50%;
  width: clamp(50px, 7.6vw, 66px);
  aspect-ratio: 1;
  z-index: 5;
  transform: translate(-50%, -50%);
  filter: drop-shadow(0 5px 7px rgba(80, 50, 40, 0.4));
  transition: transform 0.5s ease, opacity 0.5s ease;
}
.env-seal img { width: 100%; display: block; }
.envelope.is-open .env-seal {
  transform: translate(-50%, 40%) scale(0.35) rotate(24deg);
  opacity: 0;
}

/* ── 8. Hint + CTA ─────────────────────────────────────────────── */
.hero-hint {
  font-family: var(--font-hand);
  font-size: clamp(1.05rem, 2.6vw, 1.3rem);
  font-weight: 500;
  color: var(--ink-soft);
  margin: 8px 0 20px;
  animation: breathe 3.4s ease-in-out infinite;
}

.btn-cta {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 26px;
  border-radius: 999px;
  border: 1px solid rgba(157, 107, 107, 0.55);
  background: rgba(255, 253, 247, 0.65);
  color: var(--accent);
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: clamp(0.82rem, 2vw, 0.98rem);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  cursor: pointer;
  box-shadow: 0 8px 20px -10px rgba(90, 64, 44, 0.35);
  transition: transform 0.3s ease, box-shadow 0.3s ease, background 0.3s ease;
}
.btn-cta:hover {
  transform: translateY(-2px);
  background: var(--paper);
  box-shadow: 0 14px 28px -12px rgba(90, 64, 44, 0.4);
}
.btn-cta:active { transform: translateY(0) scale(0.99); }
.btn-cta .btn-cta-arrow { transition: transform 0.3s ease; }
.btn-cta:hover .btn-cta-arrow { transform: translateX(4px); }

/* ── 9. Chapter headings ───────────────────────────────────────── */
.chapter-head { margin: 0 0 clamp(36px, 6vh, 58px); }
.chapter-kicker {
  font-family: var(--font-hand);
  font-size: clamp(1.05rem, 2.4vw, 1.25rem);
  color: var(--accent);
  margin: 0 0 8px;
}
.chapter-kicker i { margin-right: 6px; font-size: 0.9em; }
.chapter-title {
  font-family: var(--font-serif);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.28em;
  font-size: clamp(1rem, 2.8vw, 1.4rem);
  color: var(--ink);
  margin: 0;
  padding-left: 0.28em;
}
.chapter-sub {
  font-family: var(--font-hand);
  font-size: clamp(1.05rem, 2.6vw, 1.3rem);
  color: var(--ink-soft);
  margin: 10px 0 0;
}
.chapter-rule {
  width: 72px;
  height: 1px;
  margin: 16px auto 0;
  background: linear-gradient(90deg, transparent, var(--accent-3), transparent);
}

/* ── 10. PAGE 2 · the letter ───────────────────────────────────── */
.letter-paper {
  position: relative;
  width: min(740px, 100%);
  background: linear-gradient(175deg, var(--paper) 0%, #FBF4E7 55%, #F6ECD9 100%);
  border-radius: 12px;
  border: 1px solid rgba(140, 110, 80, 0.16);
  box-shadow: var(--shadow-paper);
  padding: clamp(32px, 6vw, 66px) clamp(22px, 5vw, 58px) clamp(36px, 7vw, 72px);
  transform: rotate(-0.4deg);
}

.letter-paper::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 12px;
  pointer-events: none;
  background:
    radial-gradient(60px 40px at 88% 10%, rgba(200, 162, 122, 0.16), transparent 70%),
    radial-gradient(48px 32px at 7% 88%, rgba(157, 107, 107, 0.1), transparent 70%),
    radial-gradient(72px 52px at 94% 80%, rgba(200, 162, 122, 0.1), transparent 70%);
}
.letter-paper::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 12px;
  pointer-events: none;
  box-shadow: inset 0 0 70px rgba(140, 110, 80, 0.16);
}
.paper-grain {
  position: absolute;
  inset: 0;
  border-radius: 12px;
  background-image: var(--noise);
  opacity: 0.45;
  mix-blend-mode: multiply;
  pointer-events: none;
}

.letter-note {
  position: absolute;
  top: 16px;
  right: 20px;
  margin: 0;
  font-family: var(--font-hand);
  font-size: clamp(0.95rem, 2.2vw, 1.15rem);
  color: var(--accent-2);
  transform: rotate(3deg);
  opacity: 0.9;
  z-index: 2;
  pointer-events: none;
}
.letter-note i { margin-right: 5px; font-size: 0.85em; }

.letter-bouquet-wrap {
  display: block;
  margin-top: clamp(22px, 4vh, 38px);
  pointer-events: none;
}
.letter-bouquet-wrap.reveal-line.is-visible {
  opacity: 0.85;
  filter: blur(0);
}
.letter-bouquet {
  display: block;
  width: clamp(64px, 11vw, 104px);
  margin: 0 auto;
  animation: bouquetFloat 6.5s ease-in-out infinite;
}

.letter-greeting {
  font-family: var(--font-serif);
  font-style: italic;
  font-weight: 500;
  font-size: clamp(1.5rem, 4vw, 2rem);
  color: var(--ink);
  margin: 0 0 0.7em;
}

.letter-body p {
  font-family: var(--font-read);
  font-weight: 400;
  font-size: clamp(1.05rem, 1.8vw, 1.24rem);
  line-height: 1.9;
  color: var(--ink-soft);
  margin: 0 0 1.15em;
}

.letter-signoff {
  font-family: var(--font-serif);
  font-style: italic;
  font-size: clamp(1.15rem, 3vw, 1.45rem);
  color: var(--ink);
  margin: 1.8em 0 0.2em;
}
.letter-signature {
  font-family: var(--font-hand);
  font-weight: 600;
  font-size: clamp(1.7rem, 5vw, 2.3rem);
  color: var(--ink);
  margin: 0;
  line-height: 1.2;
}
.letter-endmark {
  text-align: center;
  color: var(--accent);
  font-size: 1.1rem;
  margin: 2em 0 0;
}

.reveal-line {
  opacity: 0;
  transform: translateY(14px);
  filter: blur(2px);
  transition: opacity 0.8s ease, transform 0.8s var(--ease-out), filter 0.8s ease;
  transition-delay: var(--d, 0s);
}
.reveal-line.is-visible { opacity: 1; transform: none; filter: blur(0); }

/* ── 11. PAGE 3 · little memories ──────────────────────────────── */
.photo-stack {
  position: relative;
  width: min(350px, 92vw);
  margin: 0 auto;
  -webkit-user-select: none;
  user-select: none;
}

.stack-stage {
  position: relative;
  display: grid;
  grid-template-areas: "card";
  grid-template-columns: 1fr;
  justify-items: center;
  width: 100%;
  transform: translateX(calc(var(--drag, 0) * 20px));
  transition: transform 0.5s var(--ease-out);
  touch-action: pan-y;
  cursor: grab;
}
.stack-stage.is-dragging,
.stack-stage.is-dragging .polaroid { transition: none; cursor: grabbing; }

.polaroid {
  grid-area: card;
  width: min(330px, 88vw);
  background: var(--paper);
  padding: 12px 12px 18px;
  border-radius: 4px;
  box-shadow: 0 16px 34px -18px rgba(74, 55, 41, 0.4), 0 2px 6px rgba(74, 55, 41, 0.12);
  transform: translateX(var(--px, 0px)) rotate(var(--pr, var(--rot, 0deg))) scale(var(--ps, 1));
  opacity: var(--po, 1);
  z-index: var(--pz, 1);
  transition: transform 0.75s var(--ease-spring), opacity 0.5s ease, box-shadow 0.4s ease;
  position: relative;
  will-change: transform;
}

.polaroid[data-pos="0"]  { --px: 0;     --pr: var(--rot, 0deg); --ps: 1;    --pz: 7; --po: 1; }
.polaroid[data-pos="-1"] { --px: -58%;  --pr: -8deg;            --ps: 0.88; --pz: 6; --po: 0.92; }
.polaroid[data-pos="1"]  { --px: 58%;   --pr: 8deg;             --ps: 0.88; --pz: 5; --po: 0.92; }
.polaroid[data-pos="-2"] { --px: -100%; --pr: -15deg;           --ps: 0.78; --pz: 4; --po: 0.5; }
.polaroid[data-pos="2"]  { --px: 100%;  --pr: 15deg;            --ps: 0.78; --pz: 3; --po: 0.5; }
.polaroid[data-pos="-3"] { --px: -138%; --pr: -20deg;           --ps: 0.7;  --pz: 2; --po: 0.25; }
.polaroid[data-pos="3"]  { --px: 138%;  --pr: 20deg;            --ps: 0.7;  --pz: 2; --po: 0.25; }
.polaroid:not([data-pos="0"]) { pointer-events: none; }
.polaroid[data-pos="-1"],
.polaroid[data-pos="1"] { pointer-events: auto; cursor: pointer; }

.polaroid[data-pos="0"]:hover {
  transform: translateX(var(--px, 0px)) rotate(var(--pr, var(--rot, 0deg))) scale(1.02) translateY(-8px);
  box-shadow: 0 28px 48px -22px rgba(74, 55, 41, 0.5), 0 4px 10px rgba(74, 55, 41, 0.14);
}

/* navigation arrows + counter */
.stack-nav {
  position: absolute;
  top: 38%;
  z-index: 10;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid rgba(157, 107, 107, 0.4);
  background: rgba(255, 253, 247, 0.85);
  color: var(--accent);
  font-size: 1.15rem;
  display: grid;
  place-items: center;
  cursor: pointer;
  box-shadow: 0 6px 16px -8px rgba(90, 64, 44, 0.35);
  transition: transform 0.3s ease, background 0.3s ease, opacity 0.3s ease;
  -webkit-tap-highlight-color: transparent;
}
.stack-prev { left: -14px; }
.stack-next { right: -14px; }
.stack-nav:hover:not(.is-disabled) { background: var(--paper); transform: scale(1.1); }
.stack-nav:active:not(.is-disabled) { transform: scale(0.92); }
.stack-nav.is-disabled { opacity: 0.3; cursor: default; }

.stack-count {
  margin: 20px 0 0;
  font-family: var(--font-hand);
  font-size: 1.15rem;
  letter-spacing: 0.14em;
  color: var(--ink-soft);
}
.stack-index { color: var(--accent); font-weight: 600; }
.stack-total { opacity: 0.65; }

.polaroid--tape::before {
  content: "";
  position: absolute;
  top: -12px;
  left: 50%;
  transform: translateX(-50%) rotate(var(--tape-rot, 0deg));
  width: 92px;
  height: 24px;
  background: rgba(228, 209, 166, 0.6);
  box-shadow: 0 1px 3px rgba(90, 64, 44, 0.18);
  border-left: 1px dashed rgba(120, 90, 60, 0.25);
  border-right: 1px dashed rgba(120, 90, 60, 0.25);
  z-index: 2;
}

/* photo area */
.photo-frame {
  position: relative;
  aspect-ratio: 4 / 5;
  border-radius: 2px;
  overflow: hidden;
  background-image: var(--scene-grad);
  background-size: cover;
  background-position: center;
  box-shadow: inset 0 0 0 1px rgba(120, 90, 60, 0.14);
  color: rgba(78, 64, 56, 0.55);
}
.photo-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: radial-gradient(125% 125% at 50% 38%, transparent 55%, rgba(60, 40, 25, 0.3) 100%);
}

.film-grain {
  position: absolute;
  inset: 0;
  background-image: var(--noise);
  opacity: 0.4;
  mix-blend-mode: multiply;
  pointer-events: none;
}

/* placeholder scenes */
.scene-rain   { --scene-grad: linear-gradient(160deg, #C9CFD2 0%, #AEB7BB 55%, #97A2A8 100%); }
.scene-coffee { --scene-grad: linear-gradient(150deg, #E6D6BF 0%, #D9C3A4 60%, #C9AD8B 100%); }
.scene-night  { --scene-grad: linear-gradient(165deg, #3E3A4E 0%, #4C4560 50%, #6B5F78 100%); color: rgba(255, 240, 225, 0.55); }
.scene-smile  { --scene-grad: linear-gradient(160deg, #EAC998 0%, #DFB57F 55%, #D2A06B 100%); }

/* captions */
.polaroid figcaption { padding: 12px 4px 2px; text-align: center; }
.p-num {
  display: block;
  font-family: var(--font-serif);
  font-size: 0.7rem;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 6px;
}
.p-title {
  display: block;
  font-family: var(--font-hand);
  font-weight: 600;
  font-size: clamp(1.25rem, 3vw, 1.5rem);
  line-height: 1.15;
  color: var(--ink);
}
.p-date {
  display: block;
  font-family: var(--font-serif);
  font-size: 0.66rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--ink-soft);
  opacity: 0.75;
  margin: 7px 0 8px;
}
.p-text {
  font-family: var(--font-read);
  font-size: clamp(0.9rem, 2vw, 1rem);
  line-height: 1.7;
  color: var(--ink-soft);
  margin: 0;
}

.memories-note {
  text-align: center;
  font-family: var(--font-hand);
  font-size: clamp(1.05rem, 2.6vw, 1.3rem);
  color: var(--ink-soft);
  margin: clamp(44px, 8vh, 70px) 0 0;
}
.memories-note i { color: var(--accent); margin-right: 7px; }

/* ── 13. Back + continue buttons ───────────────────────────────── */
.page-back {
  position: absolute;
  top: max(18px, env(safe-area-inset-top));
  left: max(18px, env(safe-area-inset-left));
  z-index: 5;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 8px 10px;
  background: none;
  border: 0;
  color: var(--ink-soft);
  font-family: var(--font-hand);
  font-size: 1.15rem;
  font-weight: 500;
  cursor: pointer;
  opacity: 0.8;
  transition: opacity 0.3s ease, transform 0.3s ease;
}
.page-back:hover { opacity: 1; transform: translateX(-2px); }
.page-back i { font-size: 1rem; }

.btn-continue {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: clamp(40px, 7vh, 56px) auto 0;
  padding: 13px 24px;
  border-radius: 999px;
  border: 1px solid rgba(78, 64, 56, 0.35);
  background: rgba(255, 253, 247, 0.6);
  color: var(--ink);
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 0.82rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  cursor: pointer;
  box-shadow: 0 8px 20px -12px rgba(90, 64, 44, 0.3);
  transition: transform 0.3s ease, background 0.3s ease, box-shadow 0.3s ease;
}
.btn-continue:hover {
  transform: translateY(-2px);
  background: var(--paper);
  box-shadow: 0 14px 28px -14px rgba(90, 64, 44, 0.4);
}
.btn-continue i { transition: transform 0.35s var(--ease-out); }
.btn-continue:hover i { transform: translateX(4px); }

/* ── 14. Ambient dust particles ────────────────────────────────── */
.dust-layer {
  position: fixed;
  inset: 0;
  z-index: 50;
  pointer-events: none;
  overflow: hidden;
}
.dust {
  position: absolute;
  bottom: -24px;
  border-radius: 50%;
  background: radial-gradient(circle at 35% 35%, rgba(255, 252, 240, 0.95), rgba(200, 162, 122, 0.4) 60%, transparent);
  opacity: 0;
  animation: floatUp linear infinite;
  will-change: transform, opacity;
}
.dust-heart {
  position: absolute;
  bottom: -30px;
  color: var(--accent-2);
  opacity: 0;
  animation: floatUp linear infinite;
  will-change: transform, opacity;
}

.dust-petal {
  position: absolute;
  top: -40px;
  border-radius: 150% 0 150% 0;
  background:
    radial-gradient(circle at 32% 28%, rgba(255, 253, 247, 0.5), transparent 60%),
    linear-gradient(140deg, var(--petal-a, #D89A9A), var(--petal-b, #B98585));
  box-shadow: inset 0 0 1px rgba(120, 90, 60, 0.3);
  opacity: 0;
  animation: petalFall linear infinite;
  will-change: transform, opacity;
}

.dust-sparkle {
  position: absolute;
  background: radial-gradient(circle, #FFFDF7 0%, rgba(200, 162, 122, 0.9) 42%, transparent 72%);
  clip-path: polygon(50% 0%, 60% 40%, 100% 50%, 60% 60%, 50% 100%, 40% 60%, 0% 50%, 40% 40%);
  opacity: 0;
  animation: sparkleTwinkle ease-in-out infinite;
  will-change: transform, opacity;
}

/* one-shot bursts */
.burst {
  position: fixed;
  z-index: 75;
  pointer-events: none;
}
.burst-heart,
.burst-spark {
  position: absolute;
  left: 0;
  top: 0;
  animation: burstFly var(--dur, 1.3s) cubic-bezier(0.22, 1, 0.36, 1) forwards;
  will-change: transform, opacity;
}
.burst-heart { font-size: 14px; }
.burst-spark {
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: radial-gradient(circle, #FFFDF7, rgba(200, 162, 122, 0.9) 55%, transparent);
}

/* cursor sparkle */
.cursor-spark {
  position: fixed;
  z-index: 74;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: radial-gradient(circle, #FFFDF7 0%, rgba(200, 162, 122, 0.85) 50%, transparent 75%);
  pointer-events: none;
  animation: cursorFade 0.9s ease-out forwards;
  will-change: transform, opacity;
}

/* ── 15. Keyframes ─────────────────────────────────────────────── */
@keyframes riseIn {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: none; }
}
@keyframes envIn {
  from { opacity: 0; transform: translateY(30px) scale(0.95); }
  to   { opacity: 1; transform: none; }
}
@keyframes paperIn {
  from { opacity: 0; transform: rotate(-1.6deg) scale(0.97); filter: blur(8px); }
  to   { opacity: 1; transform: rotate(-0.4deg) scale(1); filter: blur(0); }
}
@keyframes cardIn {
  from { opacity: 0; transform: translateY(36px) rotate(calc(var(--rot, 0deg) + 8deg)) scale(0.94); }
  to   { opacity: var(--po, 1); transform: translateX(var(--px, 0px)) rotate(var(--pr, var(--rot, 0deg))) scale(var(--ps, 1)); }
}
@keyframes draw {
  to { stroke-dashoffset: 0; }
}
@keyframes twinkle {
  0%, 100% { opacity: 0.6; transform: scale(0.96); }
  50%      { opacity: 1;   transform: scale(1.06); }
}
@keyframes heartPulse {
  0%, 100% { transform: scale(1); }
  50%      { transform: scale(1.12); }
}
@keyframes breathe {
  0%, 100% { opacity: 0.75; }
  50%      { opacity: 1; }
}
@keyframes floatUp {
  0%   { transform: translateY(0) translateX(0); opacity: 0; }
  8%   { opacity: var(--o, 0.2); }
  90%  { opacity: var(--o, 0.2); }
  100% { transform: translateY(-110vh) translateX(var(--drift, 20px)); opacity: 0; }
}
@keyframes petalFall {
  0%   { transform: translate3d(0, -8vh, 0) rotate(0deg); opacity: 0; }
  6%   { opacity: var(--o, 0.4); }
  85%  { opacity: var(--o, 0.4); }
  100% { transform: translate3d(var(--sway, 60px), 112vh, 0) rotate(var(--spin, 400deg)); opacity: 0; }
}
@keyframes sparkleTwinkle {
  0%, 100% { opacity: 0; transform: scale(0.3); }
  50%      { opacity: var(--o, 0.7); transform: scale(1); }
}
@keyframes bouquetFloat {
  0%, 100% { transform: translateY(0) rotate(5deg); }
  50%      { transform: translateY(-9px) rotate(-1deg); }
}
@keyframes burstFly {
  0%   { transform: translate(0, 0) scale(0.4) rotate(0deg); opacity: 0; }
  12%  { opacity: 1; }
  100% { transform: translate(var(--tx, 0px), var(--ty, -80px)) scale(var(--sc, 1)) rotate(var(--rot, 24deg)); opacity: 0; }
}
@keyframes cursorFade {
  0%   { opacity: 0.85; transform: translate(0, 0) scale(1); }
  100% { opacity: 0; transform: translate(var(--mx, -5px), var(--my, -5px)) scale(0.15); }
}

/* ── 16. Responsive ────────────────────────────────────────────── */
@media (max-height: 720px) {
  .page-envelope .page-inner { padding-top: 24px; padding-bottom: 30px; }
  .envelope { margin-top: 14px; margin-bottom: 10px; width: min(430px, 82vw); }
  .hero-title { font-size: clamp(1.5rem, 4.6vw, 2.4rem); }
  .hero-heart { margin: 10px 0 2px; }
  .hero-hint { margin: 4px 0 12px; }
}

@media (max-width: 430px) {
  .envelope { width: min(400px, 88vw); margin-top: 24px; }
  .hero-title { font-size: clamp(1.5rem, 6.6vw, 2rem); }
  .music-toggle { width: 42px; height: 42px; font-size: 1.05rem; }
  .btn-cta { padding: 13px 22px; font-size: 0.8rem; }
  .letter-note { top: 12px; right: 14px; }
  .hero-bouquet { opacity: 0.5; }
  .letter-bouquet-wrap.reveal-line.is-visible { opacity: 0.65; }
  .page-inner { padding-left: 14px; padding-right: 14px; }
  .stack-nav { width: 40px; height: 40px; font-size: 1rem; }
  .stack-prev { left: -4px; }
  .stack-next { right: -4px; }
}

@media (max-width: 360px) {
  .env-letter .env-peek-3 { display: none; }
  .env-letter p { line-height: 1.4; margin-bottom: 4px; }
  .hero-hint { margin-bottom: 16px; }
  .chapter-title { letter-spacing: 0.2em; padding-left: 0.2em; }
  .page-back span { display: none; }
}

@media (hover: none) {
  .btn-cta:hover, .music-toggle:hover, .btn-continue:hover, .stack-nav:hover { transform: none; }
}

/* ── 17. Reduced motion ────────────────────────────────────────── */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    transition-delay: 0s !important;
  }
  .dust-layer { display: none; }
  .hero-bouquet, .letter-bouquet-wrap { display: none; }
  .burst, .cursor-spark { display: none !important; }
  .hero-star, .hero-heart, .hero-hint, .music-toggle.is-playing i { animation: none; }

  * { scrollbar-color: var(--accent-2) rgba(157, 107, 107, 0.1); }
  ::-webkit-scrollbar-thumb {
    background: linear-gradient(180deg, var(--accent-2) 0%, var(--accent) 100%);
    background-clip: padding-box;
  }
}