/* ===== DESIGN TOKENS ===== */
:root {
  --bg-primary: #1a0a1e;
  --bg-secondary: #2d1233;
  --bg-card: rgba(255, 255, 255, 0.06);
  --accent-rose: #e8758a;
  --accent-pink: #f4a0b5;
  --accent-blush: #fcd5dc;
  --accent-gold: #d4a853;
  --accent-lavender: #b8a9d4;
  --text-primary: #fff5f7;
  --text-secondary: #d4b8c4;
  --text-muted: #9a7b8a;
  --shadow-glow: 0 0 40px rgba(232, 117, 138, 0.25);
  --shadow-soft: 0 8px 32px rgba(0, 0, 0, 0.3);
  --font-display: 'Playfair Display', serif;
  --font-body: 'Outfit', sans-serif;
  --transition-smooth: all 0.5s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-bounce: all 0.6s cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* ===== RESET & BASE ===== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-body);
  background: var(--bg-primary);
  color: var(--text-primary);
  overflow-x: hidden;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ===== ANIMATED BACKGROUND ===== */
.bg-gradient {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
  background: 
    radial-gradient(ellipse at 20% 50%, rgba(232, 117, 138, 0.15) 0%, transparent 50%),
    radial-gradient(ellipse at 80% 20%, rgba(184, 169, 212, 0.12) 0%, transparent 50%),
    radial-gradient(ellipse at 50% 80%, rgba(212, 168, 83, 0.08) 0%, transparent 50%),
    var(--bg-primary);
  animation: bgShift 12s ease-in-out infinite alternate;
}

@keyframes bgShift {
  0% { opacity: 1; }
  50% { opacity: 0.85; }
  100% { opacity: 1; }
}

/* ===== FLOATING PARTICLES ===== */
.particles {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 0;
  overflow: hidden;
}

.particle {
  position: absolute;
  opacity: 0;
  animation: floatUp linear infinite;
}

.particle svg {
  width: 100%;
  height: 100%;
  fill: currentColor;
}

@keyframes floatUp {
  0% {
    transform: translateY(100vh) rotate(0deg) scale(0.5);
    opacity: 0;
  }
  10% {
    opacity: 0.6;
  }
  90% {
    opacity: 0.3;
  }
  100% {
    transform: translateY(-10vh) rotate(360deg) scale(1);
    opacity: 0;
  }
}

/* ===== ONBOARDING SCREEN ===== */
#onboarding {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 1000;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: var(--bg-primary);
  transition: var(--transition-smooth);
}

#onboarding.fade-out {
  opacity: 0;
  transform: scale(1.05);
  pointer-events: none;
}

.onboarding-content {
  text-align: center;
  max-width: 600px;
  padding: 2rem;
  animation: fadeInUp 1.2s cubic-bezier(0.4, 0, 0.2, 1) forwards;
  opacity: 0;
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(40px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.onboarding-icons {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.2rem;
  margin-bottom: 2rem;
  animation: fadeInUp 1.2s 0.3s cubic-bezier(0.4, 0, 0.2, 1) forwards;
  opacity: 0;
}

.onboarding-icon {
  width: 36px;
  height: 36px;
  color: var(--accent-rose);
  animation: pulse 2s ease-in-out infinite;
  filter: drop-shadow(0 0 8px rgba(232, 117, 138, 0.4));
}

.onboarding-icon:nth-child(2) {
  animation-delay: 0.3s;
  color: var(--accent-pink);
}

.onboarding-icon:nth-child(3) {
  animation-delay: 0.6s;
  color: var(--accent-gold);
}

.onboarding-icon:nth-child(4) {
  animation-delay: 0.9s;
  color: var(--accent-lavender);
}

.onboarding-icon:nth-child(5) {
  animation-delay: 1.2s;
  color: var(--accent-blush);
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.15); }
}

.onboarding-title {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 5vw, 3.2rem);
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 0.8rem;
  background: linear-gradient(135deg, var(--accent-rose), var(--accent-pink), var(--accent-gold));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: fadeInUp 1.2s 0.6s cubic-bezier(0.4, 0, 0.2, 1) forwards;
  opacity: 0;
}

.onboarding-subtitle {
  font-family: var(--font-body);
  font-size: clamp(0.95rem, 2.5vw, 1.2rem);
  color: var(--text-secondary);
  margin-bottom: 2.5rem;
  font-weight: 300;
  letter-spacing: 0.02em;
  animation: fadeInUp 1.2s 0.9s cubic-bezier(0.4, 0, 0.2, 1) forwards;
  opacity: 0;
}

.onboarding-divider {
  width: 60px;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent-rose), transparent);
  margin: 0 auto 2.5rem;
  animation: fadeInUp 1.2s 1s cubic-bezier(0.4, 0, 0.2, 1) forwards;
  opacity: 0;
}

.btn-continue {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  padding: 1rem 2.8rem;
  background: linear-gradient(135deg, var(--accent-rose), #d4668a);
  color: #fff;
  border: none;
  border-radius: 50px;
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 500;
  letter-spacing: 0.05em;
  cursor: pointer;
  transition: var(--transition-bounce);
  box-shadow: 0 4px 20px rgba(232, 117, 138, 0.4);
  animation: fadeInUp 1.2s 1.2s cubic-bezier(0.4, 0, 0.2, 1) forwards;
  opacity: 0;
  overflow: hidden;
}

.btn-continue::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
  transition: left 0.6s ease;
}

.btn-continue:hover::before {
  left: 100%;
}

.btn-continue:hover {
  transform: translateY(-3px) scale(1.03);
  box-shadow: 0 8px 30px rgba(232, 117, 138, 0.5);
}

.btn-continue:active {
  transform: translateY(-1px) scale(0.98);
}

.btn-continue svg {
  width: 18px;
  height: 18px;
  transition: transform 0.3s ease;
}

.btn-continue:hover svg {
  transform: translateX(4px);
}

/* ===== MAIN APP ===== */
#main-app {
  display: none;
  opacity: 0;
  transition: opacity 0.8s ease;
  min-height: 100vh;
  padding: 2rem 1rem;
}

#main-app.visible {
  display: block;
  opacity: 1;
}

/* ===== PAGE HEADER ===== */
.page-header {
  text-align: center;
  padding: 2rem 1rem 1.5rem;
  animation: fadeInUp 0.8s ease forwards;
}

.page-header-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.4rem 1.2rem;
  background: var(--bg-card);
  border: 1px solid rgba(232, 117, 138, 0.2);
  border-radius: 50px;
  font-size: 0.8rem;
  color: var(--accent-pink);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 1rem;
  backdrop-filter: blur(10px);
}

.page-header-badge svg {
  width: 14px;
  height: 14px;
}

.page-header h1 {
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 4vw, 2.6rem);
  font-weight: 700;
  background: linear-gradient(135deg, var(--accent-rose), var(--accent-pink), var(--accent-lavender));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.5rem;
}

.page-header p {
  color: var(--text-secondary);
  font-size: clamp(0.85rem, 2vw, 1rem);
  font-weight: 300;
}

/* ===== ANIMEJS TIMELINE ===== */
.timeline-wrapper {
  position: relative;
  max-width: 600px;
  margin: 0 auto 2.5rem;
  padding: 1rem 1.5rem;
}

.timeline-track-bg {
  position: absolute;
  top: 2.1rem;
  left: 3rem;
  right: 3rem;
  height: 4px;
  background: rgba(255, 255, 255, 0.08);
  border-radius: 4px;
  z-index: 1;
}

.timeline-track-progress {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--accent-rose), var(--accent-pink), var(--accent-gold));
  border-radius: 4px;
  box-shadow: 0 0 12px rgba(232, 117, 138, 0.6);
  transition: width 0.1s linear;
}

.timeline-nodes {
  position: relative;
  display: flex;
  justify-content: space-between;
  align-items: center;
  z-index: 2;
}

.timeline-node {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0 0.5rem;
  outline: none;
  user-select: none;
}

.node-ring {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: rgba(26, 10, 30, 0.9);
  border: 2px solid rgba(232, 117, 138, 0.3);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: border-color 0.3s ease, box-shadow 0.3s ease;
  backdrop-filter: blur(10px);
}

.node-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--text-muted);
  transition: background-color 0.3s ease, transform 0.3s ease;
}

.node-year {
  font-family: var(--font-body);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-muted);
  letter-spacing: 0.05em;
  transition: color 0.3s ease, transform 0.3s ease;
}

.timeline-node:hover .node-ring {
  border-color: var(--accent-rose);
  box-shadow: 0 0 15px rgba(232, 117, 138, 0.4);
}

.timeline-node:hover .node-year {
  color: var(--accent-pink);
}

.timeline-node.active .node-ring {
  border-color: var(--accent-rose);
  box-shadow: 0 0 20px rgba(232, 117, 138, 0.6);
}

.timeline-node.active .node-dot {
  background: var(--accent-rose);
  transform: scale(1.2);
}

.timeline-node.active .node-year {
  color: var(--text-primary);
  font-weight: 600;
}

/* ===== FLIPBOOK CONTAINER ===== */
.flipbook-wrapper {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  position: relative;
}

.flipbook-container {
  position: relative;
  perspective: 2000px;
}

#flipbook {
  position: relative;
  margin: 0 auto;
  -webkit-user-select: none;
  -moz-user-select: none;
  user-select: none;
  cursor: grab;
}

#flipbook:active {
  cursor: grabbing;
}

#flipbook .page {
  background: #fdf6f0;
  overflow: hidden;
}

/* All page children must not capture mouse events,
   so turn.js can handle drag on the .page itself */
#flipbook .page-content,
#flipbook .page-photo,
#flipbook .page-caption,
#flipbook .page-caption h3,
#flipbook .page-caption span,
#flipbook .page-number,
#flipbook .cover-page h2,
#flipbook .cover-page p,
#flipbook .cover-page .cover-icon {
  pointer-events: none;
}

#flipbook .page-content {
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
  position: relative;
}

/* ===== PHOTO LOADING PLACEHOLDER (PINK + HEART LOADER) ===== */
.photo-loader-bg {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, #fce4ec 0%, #f8bbd0 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1;
  pointer-events: none;
}

/* User's Custom Heart Loader */
.loader {
  width: 50px;
  aspect-ratio: 1;
  color: #e8758a;
  background:
   radial-gradient(circle at 60% 65%, currentColor 62%, #0000 65%) top left,
   radial-gradient(circle at 40% 65%, currentColor 62%, #0000 65%) top right,
   linear-gradient(to bottom left, currentColor 42%,#0000 43%) bottom left ,
   linear-gradient(to bottom right,currentColor 42%,#0000 43%) bottom right;
  background-size: 50% 50%;
  background-repeat: no-repeat;
  position: relative;
}
.loader:after {
  content: "";
  position: absolute;
  inset: 0;
  background: inherit;
  opacity: 0.4;
  animation: l3 1s infinite;
}
@keyframes l3 {
  to {transform:scale(1.8);opacity:0}
}

#flipbook .page-photo {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  z-index: 2;
  opacity: 0;
  transition: opacity 0.4s ease;
  -webkit-user-drag: none;
  -khtml-user-drag: none;
  -moz-user-drag: none;
  -o-user-drag: none;
  user-drag: none;
  -webkit-user-select: none;
  user-select: none;
}

#flipbook .page-photo.loaded {
  opacity: 1;
}

/* Cover pages */
#flipbook .cover-page {
  background: linear-gradient(145deg, #2d1233, #1a0a1e);
  position: relative;
  overflow: hidden;
}

/* Fixed-size inner wrapper prevents content morphing during flip animation.
   Turn.js dynamically changes the .page width during animation, but this
   inner div keeps its explicit pixel dimensions stable. */
#flipbook .cover-inner {
  position: absolute;
  top: 0;
  left: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 2rem;
  pointer-events: none;
}

#flipbook .cover-page .cover-icon {
  width: 48px;
  height: 48px;
  color: var(--accent-rose);
  margin-bottom: 1.5rem;
  filter: drop-shadow(0 0 12px rgba(232, 117, 138, 0.5));
}

#flipbook .cover-page h2 {
  font-family: var(--font-display);
  font-size: clamp(1.2rem, 3vw, 1.8rem);
  color: var(--accent-blush);
  margin-bottom: 0.5rem;
  white-space: nowrap;
}

#flipbook .cover-page p {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 300;
  white-space: nowrap;
}

/* Year divider pages (section breaks within the book) */
#flipbook .year-divider {
  background: linear-gradient(145deg, #2d1233, #1f0d26);
}

/* Photo pages with caption overlay */
#flipbook .photo-page {
  position: relative;
}

#flipbook .page-caption {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  padding: 1.5rem 1rem 1rem;
  background: linear-gradient(transparent, rgba(26, 10, 30, 0.85));
  color: #fff;
}

#flipbook .page-caption h3 {
  font-family: var(--font-display);
  font-size: clamp(0.8rem, 2vw, 1rem);
  margin-bottom: 0.25rem;
  font-weight: 600;
}

#flipbook .page-caption span {
  font-size: 0.7rem;
  color: var(--accent-pink);
  font-weight: 300;
  letter-spacing: 0.05em;
}

/* ===== NAVIGATION CONTROLS ===== */
.book-nav {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 2rem;
  margin-top: 1.5rem;
}

.nav-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: 1px solid rgba(232, 117, 138, 0.3);
  background: var(--bg-card);
  color: var(--accent-pink);
  cursor: pointer;
  transition: var(--transition-bounce);
  backdrop-filter: blur(10px);
}

.nav-btn:hover {
  background: var(--accent-rose);
  color: #fff;
  border-color: transparent;
  box-shadow: 0 4px 16px rgba(232, 117, 138, 0.4);
  transform: scale(1.1);
}

.nav-btn:active {
  transform: scale(0.95);
}

.nav-btn svg {
  width: 20px;
  height: 20px;
}

.page-indicator {
  font-family: var(--font-body);
  font-size: 0.85rem;
  color: var(--text-muted);
  letter-spacing: 0.1em;
  min-width: 80px;
  text-align: center;
}

/* ===== BOOK TEXTURE ===== */
#flipbook .page::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: 
    linear-gradient(90deg, rgba(0,0,0,0.03) 0%, transparent 5%, transparent 95%, rgba(0,0,0,0.03) 100%);
  pointer-events: none;
  z-index: 1;
}

/* ===== PAGE NUMBER ===== */
.page-number {
  position: absolute;
  bottom: 8px;
  font-size: 0.65rem;
  color: rgba(0,0,0,0.3);
  font-family: var(--font-body);
  z-index: 2;
}

.page-number.left {
  left: 12px;
}

.page-number.right {
  right: 12px;
}

/* ===== DRAG / SWIPE HINT ===== */
.swipe-hint {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  margin-top: 1rem;
  color: var(--text-muted);
  font-size: 0.75rem;
  animation: fadeInOut 3s ease-in-out infinite;
  transition: opacity 0.5s ease;
}

.swipe-hint svg {
  width: 16px;
  height: 16px;
  animation: swipeAnim 1.5s ease-in-out infinite;
}

@keyframes swipeAnim {
  0%, 100% { transform: translateX(0); }
  50% { transform: translateX(8px); }
}

@keyframes fadeInOut {
  0%, 100% { opacity: 0.4; }
  50% { opacity: 0.8; }
}

/* ===== LOVE LETTER MODAL ===== */
.letter-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 2000;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(26, 10, 30, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.6s ease, visibility 0.6s ease;
  padding: 1.5rem;
}

.letter-overlay.visible {
  opacity: 1;
  visibility: visible;
}

.letter-card {
  position: relative;
  max-width: 520px;
  width: 100%;
  background: linear-gradient(160deg, #2d1233 0%, #1a0a1e 100%);
  border: 1px solid rgba(232, 117, 138, 0.2);
  border-radius: 24px;
  padding: 3rem 2.5rem 2.5rem;
  box-shadow:
    0 24px 80px rgba(0, 0, 0, 0.5),
    0 0 60px rgba(232, 117, 138, 0.15),
    inset 0 1px 0 rgba(255, 255, 255, 0.05);
  transform: translateY(30px) scale(0.95);
  transition: transform 0.6s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.letter-overlay.visible .letter-card {
  transform: translateY(0) scale(1);
}

.farewell-card {
  max-width: 440px;
  padding: 2.8rem 2rem 2rem;
}

.tutorial-card {
  max-width: 420px;
  padding: 2.8rem 2rem 2rem;
  text-align: center;
}

.tutorial-swipe-anim {
  width: 52px;
  height: 52px;
  margin: 0.5rem auto 1.2rem;
  color: var(--accent-pink);
  animation: swipeGuide 2.2s ease-in-out infinite;
}

.tutorial-swipe-anim svg {
  width: 100%;
  height: 100%;
}

@keyframes swipeGuide {
  0%, 100% { transform: translateX(0) rotate(0deg); }
  50% { transform: translateX(14px) rotate(-12deg); }
}

.tutorial-btn {
  margin-top: 1.5rem;
  display: inline-flex;
  padding: 0.8rem 2.4rem;
  font-size: 0.95rem;
}

.letter-seal {
  position: absolute;
  top: -28px;
  left: 50%;
  transform: translateX(-50%);
  width: 56px;
  height: 56px;
  background: linear-gradient(135deg, var(--accent-rose), #d4668a);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 20px rgba(232, 117, 138, 0.5);
  animation: sealPulse 2.5s ease-in-out infinite;
}

.letter-seal svg {
  width: 26px;
  height: 26px;
  color: #fff;
}

@keyframes sealPulse {
  0%, 100% { box-shadow: 0 4px 20px rgba(232, 117, 138, 0.5); }
  50% { box-shadow: 0 4px 35px rgba(232, 117, 138, 0.7); }
}

.letter-greeting {
  font-family: var(--font-display);
  font-size: clamp(1.4rem, 4vw, 1.9rem);
  font-weight: 700;
  background: linear-gradient(135deg, var(--accent-rose), var(--accent-pink), var(--accent-gold));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 1.5rem;
  text-align: center;
}

.letter-body {
  margin-bottom: 2rem;
}

.letter-body p {
  font-family: var(--font-body);
  font-size: clamp(0.9rem, 2.5vw, 1.02rem);
  line-height: 1.8;
  color: var(--text-secondary);
  font-weight: 300;
  margin-bottom: 1.2rem;
  text-align: left;
}

.letter-body p:last-child {
  margin-bottom: 0;
}

.letter-sign {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(232, 117, 138, 0.15);
}

.letter-sign-icon {
  width: 16px;
  height: 16px;
  color: var(--accent-rose);
  animation: pulse 2s ease-in-out infinite;
}

.letter-sign span {
  font-family: var(--font-display);
  font-size: 1rem;
  font-style: italic;
  color: var(--accent-pink);
  font-weight: 600;
}

.letter-close {
  position: absolute;
  top: 1rem;
  right: 1rem;
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  background: rgba(255, 255, 255, 0.06);
  border-radius: 50%;
  cursor: pointer;
  transition: var(--transition-smooth);
  color: var(--text-muted);
}

.letter-close svg {
  width: 18px;
  height: 18px;
}

.letter-close:hover {
  background: rgba(232, 117, 138, 0.2);
  color: var(--accent-pink);
  transform: rotate(90deg);
}

/* ===== FOOTER ===== */
.site-footer {
  text-align: center;
  padding: 3rem 1rem 2rem;
  color: var(--text-muted);
  font-size: 0.75rem;
}

.footer-heart {
  width: 14px;
  height: 14px;
  color: var(--accent-rose);
  vertical-align: middle;
  animation: pulse 2s ease-in-out infinite;
}

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
  .onboarding-content {
    padding: 1.5rem;
  }

  .onboarding-icons {
    gap: 0.8rem;
  }

  .onboarding-icon {
    width: 28px;
    height: 28px;
  }

  .btn-continue {
    padding: 0.85rem 2.2rem;
    font-size: 0.9rem;
  }

  .page-header {
    padding: 1.5rem 1rem 1rem;
  }

  .year-tabs {
    gap: 0.4rem;
  }

  .year-tab {
    padding: 0.5rem 1.2rem;
    font-size: 0.78rem;
  }

  .book-nav {
    gap: 1.2rem;
  }

  .nav-btn {
    width: 42px;
    height: 42px;
  }

  .swipe-hint {
    display: flex;
  }

  #flipbook .cover-page {
    padding: 1.5rem;
  }

  #flipbook .cover-page .cover-icon {
    width: 36px;
    height: 36px;
  }

  #flipbook .cover-page h2 {
    font-size: 1.1rem;
  }

  #flipbook .page-caption {
    padding: 1rem 0.75rem 0.75rem;
  }

  .flipbook-wrapper {
    width: 100%;
    padding: 0.5rem;
    box-sizing: border-box;
  }

  .flipbook-container {
    width: 100%;
    max-width: 100vw;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
  }

  #flipbook {
    margin: 0 auto !important;
    left: 0 !important;
  }

  #flipbook .turn-page-wrapper,
  #flipbook .page-wrapper {
    left: 0 !important;
  }

  .letter-card {
    padding: 2.5rem 1.5rem 2rem;
    border-radius: 20px;
  }

  .letter-greeting {
    font-size: 1.3rem;
  }

  .letter-body p {
    font-size: 0.88rem;
    line-height: 1.7;
  }
}

@media (max-width: 480px) {
  .onboarding-title {
    font-size: 1.6rem;
  }

  .page-header h1 {
    font-size: 1.4rem;
  }

  .year-tab {
    padding: 0.45rem 1rem;
    font-size: 0.72rem;
  }
}

/* ===== UTILITY ANIMATIONS ===== */
.fade-in {
  animation: fadeIn 0.8s ease forwards;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.slide-up {
  animation: slideUp 0.6s cubic-bezier(0.4, 0, 0.2, 1) forwards;
}

@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}