/* =============================================
   FLIPBOOK STUDIO – STYLESHEET
   ============================================= */

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg:          #08090f;
  --bg2:         #0f1117;
  --bg3:         #161925;
  --surface:     rgba(255,255,255,0.04);
  --surface-hover: rgba(255,255,255,0.08);
  --border:      rgba(255,255,255,0.08);
  --border-active: rgba(167,139,250,0.5);
  --text:        #f1f5f9;
  --text-muted:  #94a3b8;
  --text-faint:  #475569;
  --purple:      #a78bfa;
  --purple-dark: #7c3aed;
  --pink:        #f0abfc;
  --pink-dark:   #c026d3;
  --accent:      linear-gradient(135deg, #a78bfa, #f0abfc);
  --btn-grad:    linear-gradient(135deg, #7c3aed, #c026d3);
  --shadow-lg:   0 25px 60px rgba(0,0,0,0.6);
  --shadow-sm:   0 4px 20px rgba(0,0,0,0.3);
  --radius:      16px;
  --radius-sm:   10px;
  --transition:  0.3s cubic-bezier(0.4,0,0.2,1);
}

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  overflow-x: hidden;
}

/* ── Screens ── */
.screen {
  position: fixed;
  inset: 0;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.5s ease;
  z-index: 1;
}
.screen.active {
  opacity: 1;
  pointer-events: all;
  z-index: 2;
}

/* ── Animated background orbs ── */
.bg-orbs { position: fixed; inset: 0; overflow: hidden; pointer-events: none; z-index: 0; }
.orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  opacity: 0.18;
  animation: drift 12s ease-in-out infinite alternate;
}
.orb-1 { width: 500px; height: 500px; background: #7c3aed; top: -150px; left: -100px; animation-duration: 14s; }
.orb-2 { width: 400px; height: 400px; background: #c026d3; bottom: -100px; right: -80px; animation-duration: 10s; animation-delay: -4s; }
.orb-3 { width: 300px; height: 300px; background: #0ea5e9; top: 50%; left: 50%; transform: translate(-50%,-50%); animation-duration: 18s; animation-delay: -8s; }

@keyframes drift {
  0%   { transform: translate(0,0) scale(1); }
  100% { transform: translate(40px, 30px) scale(1.1); }
}

/* ====================================================
   UPLOAD SCREEN
   ==================================================== */
.site-header {
  position: relative; z-index: 10;
  display: flex; align-items: center;
  padding: 24px 40px;
}
.logo {
  display: flex; align-items: center; gap: 10px;
  font-family: 'Outfit', sans-serif;
  font-weight: 700; font-size: 1.25rem;
  background: var(--accent);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.upload-main {
  position: relative; z-index: 5;
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  min-height: calc(100vh - 90px);
  padding: 20px 24px 60px;
  gap: 40px;
}

.hero-text { text-align: center; max-width: 640px; }
.hero-text h1 {
  font-family: 'Outfit', sans-serif;
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 800;
  line-height: 1.15;
  color: var(--text);
  margin-bottom: 16px;
}
.gradient-text {
  background: var(--accent);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-text p {
  font-size: 1.05rem;
  color: var(--text-muted);
  line-height: 1.7;
}

/* Upload card */
.upload-card {
  position: relative;
  background: rgba(255,255,255,0.03);
  border: 2px dashed var(--border);
  border-radius: 24px;
  padding: 56px 48px;
  text-align: center;
  cursor: pointer;
  transition: border-color var(--transition), background var(--transition), transform var(--transition);
  backdrop-filter: blur(20px);
  width: 100%; max-width: 560px;
}
.upload-card:hover, .upload-card.drag-over {
  border-color: var(--border-active);
  background: rgba(167,139,250,0.06);
  transform: translateY(-4px);
}
.upload-card.drag-over { border-style: solid; }

.upload-icon { margin-bottom: 20px; }

.upload-card h2 {
  font-family: 'Outfit', sans-serif;
  font-size: 1.5rem; font-weight: 700;
  margin-bottom: 6px;
}
.upload-sub { color: var(--text-muted); margin-bottom: 28px; font-size: 0.95rem; }

#pdf-input {
  position: absolute; inset: 0; opacity: 0;
  cursor: pointer; width: 100%; height: 100%;
}

.btn-upload {
  position: relative; z-index: 2;
  display: inline-flex; align-items: center; gap: 8px;
  background: var(--btn-grad);
  color: #fff;
  border: none; cursor: pointer;
  padding: 14px 32px;
  border-radius: 50px;
  font-family: 'Inter', sans-serif;
  font-size: 0.95rem; font-weight: 600;
  letter-spacing: 0.02em;
  transition: transform var(--transition), box-shadow var(--transition), filter var(--transition);
  box-shadow: 0 8px 30px rgba(124,58,237,0.4);
}
.btn-upload:hover { transform: translateY(-2px) scale(1.02); box-shadow: 0 12px 40px rgba(124,58,237,0.55); filter: brightness(1.1); }
.btn-upload:active { transform: scale(0.98); }

.upload-hint { margin-top: 18px; font-size: 0.8rem; color: var(--text-faint); }

/* Feature pills */
.features-row {
  display: flex; flex-wrap: wrap; gap: 12px;
  justify-content: center;
}
.feature-pill {
  display: flex; align-items: center; gap: 8px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 50px;
  padding: 8px 18px;
  font-size: 0.85rem; color: var(--text-muted);
  backdrop-filter: blur(10px);
  transition: background var(--transition), border-color var(--transition);
}
.feature-pill:hover { background: var(--surface-hover); border-color: rgba(167,139,250,0.3); }

/* ====================================================
   PROGRESS SCREEN
   ==================================================== */
#progress-screen {
  display: flex; align-items: center; justify-content: center;
  background: var(--bg);
}

.progress-container {
  position: relative; z-index: 5;
  text-align: center;
  display: flex; flex-direction: column; align-items: center;
  gap: 20px;
  padding: 24px;
}

/* Animated book */
.progress-book { margin-bottom: 10px; }
.book-anim {
  position: relative;
  width: 80px; height: 64px;
  margin: 0 auto;
}
.book-page {
  position: absolute;
  bottom: 0; left: 50%;
  width: 36px; height: 52px;
  border-radius: 2px 8px 8px 2px;
  transform-origin: left center;
  background: linear-gradient(160deg, rgba(167,139,250,0.9), rgba(240,171,252,0.7));
}
.book-page.p1 { transform: translateX(-100%) rotateY(0deg); background: rgba(255,255,255,0.12); border-radius: 8px 2px 2px 8px; }
.book-page.p2 { transform: translateX(0%); animation: flipPage 1.6s ease-in-out infinite; }
.book-page.p3 { transform: translateX(0%); background: rgba(255,255,255,0.08); border-radius: 2px 8px 8px 2px; }

@keyframes flipPage {
  0%   { transform: translateX(0%) rotateY(0deg);    opacity:1; }
  50%  { transform: translateX(-50%) rotateY(-90deg); opacity:0.5; }
  100% { transform: translateX(-100%) rotateY(-180deg); opacity:0; }
}

.progress-container h2 {
  font-family: 'Outfit', sans-serif;
  font-size: 1.6rem; font-weight: 700;
}
.progress-container p { color: var(--text-muted); font-size: 0.95rem; }

.progress-bar-wrap {
  width: 360px; max-width: 90vw;
  height: 6px;
  background: rgba(255,255,255,0.08);
  border-radius: 50px;
  overflow: hidden;
}
.progress-bar {
  height: 100%;
  width: 0%;
  background: var(--accent);
  border-radius: 50px;
  transition: width 0.3s ease;
}
.progress-percent {
  font-size: 0.85rem;
  color: var(--purple);
  font-weight: 600;
  letter-spacing: 0.05em;
}

/* ====================================================
   FLIPBOOK SCREEN
   ==================================================== */
#flipbook-screen {
  display: flex; flex-direction: column;
  background: radial-gradient(ellipse at top, #12101f 0%, #08090f 60%);
}

/* ── Toolbar ── */
.toolbar {
  position: relative; z-index: 100;
  display: flex; align-items: center; justify-content: space-between;
  padding: 10px 20px;
  background: rgba(8,9,15,0.85);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(20px);
  gap: 12px;
  flex-shrink: 0;
}

.toolbar-left, .toolbar-center, .toolbar-right {
  display: flex; align-items: center; gap: 8px;
}
.toolbar-left { flex: 1; }
.toolbar-right { flex: 1; justify-content: flex-end; }
.toolbar-center { flex: 0 0 auto; }

.toolbar-title {
  font-weight: 600; font-size: 0.9rem;
  color: var(--text-muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 180px;
}

.tb-btn {
  display: flex; align-items: center; justify-content: center;
  width: 36px; height: 36px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-muted);
  cursor: pointer;
  transition: background var(--transition), color var(--transition), border-color var(--transition), transform var(--transition);
  flex-shrink: 0;
}
.tb-btn:hover { background: var(--surface-hover); color: var(--text); border-color: rgba(167,139,250,0.4); transform: scale(1.05); }
.tb-btn:active { transform: scale(0.95); }

.page-indicator {
  display: flex; align-items: center; gap: 6px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0 12px;
  height: 36px;
}
#page-input {
  background: none; border: none; outline: none;
  color: var(--text);
  font-family: 'Inter', sans-serif;
  font-size: 0.9rem; font-weight: 600;
  width: 40px; text-align: center;
  -moz-appearance: textfield;
}
#page-input::-webkit-outer-spin-button,
#page-input::-webkit-inner-spin-button { -webkit-appearance: none; }
#page-total { color: var(--text-faint); font-size: 0.85rem; white-space: nowrap; }

.btn-download {
  display: flex; align-items: center; gap: 8px;
  background: var(--btn-grad);
  color: #fff; border: none; cursor: pointer;
  padding: 8px 20px;
  border-radius: 50px;
  font-family: 'Inter', sans-serif;
  font-size: 0.85rem; font-weight: 600;
  transition: transform var(--transition), box-shadow var(--transition), filter var(--transition);
  box-shadow: 0 4px 20px rgba(124,58,237,0.4);
  white-space: nowrap;
}
.btn-download:hover { transform: translateY(-1px) scale(1.02); box-shadow: 0 8px 30px rgba(124,58,237,0.55); filter: brightness(1.1); }
.btn-download:active { transform: scale(0.97); }

/* ── Flipbook Stage ── */
.flipbook-stage {
  flex: 1;
  display: flex; align-items: center; justify-content: center;
  position: relative;
  overflow: hidden;
  padding: 20px;
}

.flipbook-wrapper {
  position: relative;
  display: flex; align-items: center; justify-content: center;
  width: 100%; height: 100%;
}

/* Navigation click zones */
.nav-zone {
  position: absolute;
  top: 0; bottom: 0;
  width: 40%;
  cursor: pointer;
  z-index: 10;
}
.nav-zone-left  { left: 0; }
.nav-zone-right { right: 0; }

/* ── Book ── */
.book-container {
  position: relative;
  display: flex; align-items: center; justify-content: center;
  perspective: 2800px;          /* 3D depth for page-flip effect */
}

.book {
  position: relative;
  display: flex;
  transform-style: preserve-3d;
  border-radius: 4px 8px 8px 4px;
  overflow: visible;
  /* size set by JS */
}

/* Individual page wrapper */
.page-wrap {
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 100%;
  transform-style: preserve-3d;
  transition: none; /* JS controlled */
}

/* Front / Back faces */
.page-face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  border-radius: 2px;
  overflow: hidden;
}
.page-face canvas {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: contain;
}
.page-face.back {
  transform: rotateY(180deg);
}

/* ── Page panels (static display) ── */
/* Uses <img> so object-fit:contain works correctly (canvas ignores it) */
.page-panel {
  position: absolute;
  top: 0; height: 100%;
  overflow: hidden;
  background: #fff;              /* white page background */
}
.page-panel--left  { left: 0; border-radius: 8px 2px 2px 8px; }
.page-panel--right { right: 0; border-radius: 2px 8px 8px 2px; }
.page-panel--full  { left: 0; right: 0; width: 100%; border-radius: 6px; }

.page-panel img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: contain;           /* preserves aspect ratio – letterbox in white */
}

/* Blank / cover pages */
.page-panel--blank {
  background: linear-gradient(160deg, #16102a, #0f0a1e) !important;
  display: flex; align-items: center; justify-content: center;
}

/* Spine shadow gradient at page edges */
.page-panel--left::after, .page-panel--right::after {
  content: '';
  position: absolute;
  top: 0; bottom: 0;
  width: 24px;
  pointer-events: none;
  z-index: 2;
}
.page-panel--left::after  { right: 0; background: linear-gradient(to right, transparent, rgba(0,0,0,0.12)); }
.page-panel--right::after { left: 0;  background: linear-gradient(to left,  transparent, rgba(0,0,0,0.12)); }

/* The flipping page */
.flip-page {
  position: absolute;
  top: 0;
  height: 100%;
  transform-style: preserve-3d;
  transform-origin: left center;
  width: 50%;
  z-index: 20;
}
.flip-page .face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  overflow: hidden;
}
.flip-page .face.back { transform: rotateY(180deg); }
.flip-page .face { background: #fff; }   /* white page backing */
.flip-page .face img { display: block; width: 100%; height: 100%; object-fit: contain; }

/* Shadow during flip */
.flip-page .flip-shadow {
  position: absolute;
  inset: 0;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.1s;
}
.flip-page.flipping .flip-shadow { opacity: 1; }

/* Spine */
.book-spine {
  position: absolute;
  top: 0; bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 8px;
  background: linear-gradient(180deg, #2a1a4a, #1a0e30, #2a1a4a);
  z-index: 30;
  border-radius: 2px;
  box-shadow: 0 0 12px rgba(0,0,0,0.6);
  pointer-events: none;
}

/* Book shadow on table */
.book-shadow {
  position: absolute;
  bottom: -20px; left: 5%; right: 5%;
  height: 30px;
  background: radial-gradient(ellipse, rgba(0,0,0,0.5) 0%, transparent 70%);
  filter: blur(8px);
  pointer-events: none;
}

/* Float nav buttons */
.float-nav {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  z-index: 50;
  display: flex; align-items: center; justify-content: center;
  width: 48px; height: 48px;
  background: rgba(167,139,250,0.15);
  border: 1px solid rgba(167,139,250,0.3);
  border-radius: 50%;
  color: var(--purple);
  cursor: pointer;
  backdrop-filter: blur(10px);
  transition: background var(--transition), transform var(--transition), box-shadow var(--transition);
  box-shadow: 0 4px 20px rgba(0,0,0,0.3);
}
.float-nav:hover { background: rgba(167,139,250,0.3); transform: translateY(-50%) scale(1.08); box-shadow: 0 8px 30px rgba(124,58,237,0.4); }
.float-prev { left: 12px; }
.float-next { right: 12px; }

/* ── Thumbnail strip ── */
.thumb-strip {
  flex-shrink: 0;
  background: rgba(8,9,15,0.85);
  border-top: 1px solid var(--border);
  height: 100px;
  overflow-x: auto;
  overflow-y: hidden;
  backdrop-filter: blur(20px);
}
.thumb-strip::-webkit-scrollbar { height: 4px; }
.thumb-strip::-webkit-scrollbar-track { background: transparent; }
.thumb-strip::-webkit-scrollbar-thumb { background: rgba(167,139,250,0.3); border-radius: 2px; }

.thumb-list {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  height: 100%;
}

.thumb-item {
  flex-shrink: 0;
  cursor: pointer;
  border-radius: 6px;
  overflow: hidden;
  border: 2px solid transparent;
  transition: border-color var(--transition), transform var(--transition), box-shadow var(--transition);
  position: relative;
  height: 76px;
}
.thumb-item:hover { transform: scale(1.05); box-shadow: 0 4px 16px rgba(124,58,237,0.4); }
.thumb-item.active { border-color: var(--purple); }
.thumb-item img { display: block; height: 100%; width: auto; object-fit: contain; }
.thumb-num {
  position: absolute;
  bottom: 2px; right: 4px;
  font-size: 9px;
  color: rgba(255,255,255,0.7);
  background: rgba(0,0,0,0.5);
  border-radius: 3px;
  padding: 1px 3px;
  font-weight: 600;
}

/* ====================================================
   SINGLE PAGE MODE (mobile)
   ==================================================== */
.single-page-mode .book-spine { display: none; }
.single-page-mode .thumb-strip { display: none; }

/* ====================================================
   TOAST
   ==================================================== */
.toast {
  position: fixed;
  bottom: 24px; left: 50%;
  transform: translateX(-50%) translateY(80px);
  background: rgba(167,139,250,0.15);
  border: 1px solid rgba(167,139,250,0.4);
  backdrop-filter: blur(20px);
  color: var(--text);
  padding: 12px 24px;
  border-radius: 50px;
  font-size: 0.88rem;
  font-weight: 500;
  z-index: 9999;
  transition: transform 0.4s cubic-bezier(0.34,1.56,0.64,1), opacity 0.4s ease;
  opacity: 0;
  pointer-events: none;
  white-space: nowrap;
}
.toast.show { transform: translateX(-50%) translateY(0); opacity: 1; }

/* ====================================================
   RESPONSIVE
   ==================================================== */
@media (max-width: 768px) {
  .site-header { padding: 16px 20px; }
  .upload-main { padding: 16px 16px 40px; gap: 28px; }
  .upload-card { padding: 36px 24px; }

  .toolbar-title { display: none; }
  .toolbar { padding: 8px 12px; gap: 6px; }
  .btn-download span { display: none; }
  .btn-download { padding: 8px 12px; border-radius: 8px; }

  .float-prev { left: 4px; }
  .float-next { right: 4px; }

  .thumb-strip { height: 70px; }
  .thumb-item  { height: 50px; }
}

@media (max-width: 480px) {
  .hero-text h1 { font-size: 1.8rem; }
  .toolbar-center { gap: 4px; }
  .page-indicator { padding: 0 8px; }
}

/* ====================================================
   EMPTY / COVER PAGE
   ==================================================== */
.blank-page {
  position: absolute; inset: 0;
  background: linear-gradient(160deg, #16102a, #0f0a1e);
  display: flex; align-items: center; justify-content: center;
}
.blank-page .bp-text {
  color: rgba(255,255,255,0.1);
  font-family: 'Outfit', sans-serif;
  font-size: 1rem; font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}