:root {
  --font-brand: "Humanst521 BT", "Humanst 521 BT", "Humanist 521 BT", Arial, sans-serif;
  --ink: #2B2A29;
  --ink-2: #5a5650;
  --orange: #EC671F;
  --bg: #D9DADA;
  --surface: #ffffff;
  --border: #d9dada;
}

* { box-sizing: border-box; }

html,
body {
  margin: 0;
  padding: 0;
  height: 100%;
  overflow: hidden;
  font-family: var(--font-brand);
  color: var(--ink);
  background: var(--bg);
}

body {
  display: flex;
  flex-direction: column;
}

.viewer-nav {
  position: fixed;
  top: 16px;
  left: 28px;
  right: 28px;
  z-index: 500;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 12px 0 32px;
  height: 64px;
  background: #ffffff;
  border: none;
  border-radius: 999px;
  box-shadow: 0 4px 24px rgba(0, 0, 0, .07);
  transition: background .25s, box-shadow .25s;
}

.nav-logo {
  text-decoration: none;
  display: flex;
  align-items: center;
}

.logo-plate {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 50px;
}

.logo-img {
  height: 48px;
  width: auto;
  display: block;
  filter: contrast(1.01) saturate(1.02);
}

.nav-center {
  display: flex;
  gap: 40px;
  list-style: none;
  align-items: center;
  margin: 0;
  padding: 0;
}

.nav-center a {
  font-size: 13px;
  font-weight: 500;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: #0a0a0a;
  text-decoration: none;
  transition: color .2s;
}

.nav-center a:hover { color: var(--orange); }

.nav-right {
  display: flex;
  align-items: center;
  gap: 10px;
}

.nav-cta {
  background: var(--orange);
  color: #fff;
  border: 1px solid transparent;
  padding: 12px 28px;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: .06em;
  text-transform: uppercase;
  text-decoration: none;
  white-space: nowrap;
  transition: background-color .2s ease;
}

.nav-cta:hover {
  background: #0a0a0a;
  transform: none;
  box-shadow: none;
}

.nav-call {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  text-transform: uppercase;
  letter-spacing: .06em;
  padding: 12px 28px;
}

.nav-call svg {
  width: 15px;
  height: 15px;
  flex-shrink: 0;
}

.flip-shell {
  flex: 1 1 auto;
  min-height: 0;
  padding: 88px 20px 14px;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.flip-toolbar {
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  margin-bottom: 8px;
}

.toolbar-spacer {
  display: none;
}

.back-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  border: 1px solid transparent;
  border-radius: 999px;
  background: var(--surface);
  color: var(--ink);
  margin-right: 28px;
  padding: 12px 28px;
  font-family: var(--font-brand);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: .06em;
  text-transform: uppercase;
  cursor: pointer;
  transition: background-color .2s ease, color .2s ease;
}

.back-btn svg {
  width: 15px;
  height: 15px;
  flex-shrink: 0;
}

.back-btn:hover {
  background: var(--orange);
  color: #fff;
}

.flip-stage {
  position: relative;
  flex: 1 1 auto;
  min-height: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  background: var(--bg);
}

.book-host {
  position: relative;
  width: min(1120px, calc(100vw - 170px));
  height: 100%;
  border: 0;
  border-radius: 0;
  background: transparent;
  box-shadow: none;
  overflow: hidden;
}

#flipbook {
  position: absolute;
  inset: 0;
  opacity: 0;
  pointer-events: none;
  transition: opacity .28s ease;
}

.book-host.is-open #flipbook {
  opacity: 1;
  pointer-events: auto;
}

#flipbook .stf__parent {
  width: 100%;
  height: 100%;
}

#flipbook .stf__wrapper {
  margin: 0 auto;
}

#flipbook .stf__item {
  background-color: #fff;
  border-radius: 0;
}

#flipbook .stf__itemShadow {
  box-shadow: 0 14px 22px rgba(43, 42, 41, .16);
}

.flip-page {
  background: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
}

.flip-canvas {
  width: 100%;
  height: 100%;
  display: block;
  background: #fff;
}

.book-loader {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 7;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: .03em;
  color: var(--ink-2);
  background: rgba(217, 218, 218, .76);
}

.cover-start {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  width: min(420px, calc(100% - 24px));
  aspect-ratio: 210 / 297;
  border: 0;
  border-radius: 0;
  background: #fff;
  box-shadow: 0 18px 34px rgba(43, 42, 41, .24);
  padding: 0;
  overflow: hidden;
  cursor: pointer;
  z-index: 6;
  transition: opacity .24s ease, transform .34s ease;
}

.cover-start img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  display: block;
  user-select: none;
  background: transparent;
}

.book-host.is-open .cover-start {
  opacity: 0;
  transform: translate(-58%, -50%) rotateY(-22deg);
  pointer-events: none;
}

.cover-end {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  width: min(420px, calc(100% - 24px));
  aspect-ratio: 210 / 297;
  border: 0;
  border-radius: 0;
  background: #fff;
  box-shadow: 0 18px 34px rgba(43, 42, 41, .24);
  padding: 0;
  overflow: hidden;
  cursor: pointer;
  z-index: 6;
  opacity: 0;
  pointer-events: none;
  transition: opacity .24s ease, transform .34s ease;
}

.cover-end img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  display: block;
  user-select: none;
  background: transparent;
}

.book-host.is-back-cover .cover-end {
  opacity: 1;
  pointer-events: auto;
}

.book-host.is-back-cover #flipbook {
  opacity: 0;
  pointer-events: none;
}

.book-host.is-back-cover .cover-start {
  opacity: 0;
  pointer-events: none;
}

.page-zone {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 12%;
  min-width: 56px;
  border: 0;
  background: transparent;
  z-index: 5;
  cursor: pointer;
  opacity: 0;
  pointer-events: none;
}

.book-host.is-open .page-zone {
  pointer-events: auto;
}

.page-zone-left { left: 0; }
.page-zone-right { right: 0; }

.progress-track {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 3px;
  background: rgba(43, 42, 41, .08);
  z-index: 8;
}

.progress-fill {
  height: 100%;
  width: 0;
  background: var(--orange);
  transition: width .24s ease;
}

.flip-arrow {
  width: 50px;
  height: 58px;
  border-radius: 10px;
  border: 1px solid color-mix(in srgb, var(--ink) 16%, transparent);
  background: #fff;
  color: var(--ink);
  font-size: 30px;
  line-height: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: 0 8px 18px rgba(43, 42, 41, .12);
  transition: transform .18s ease, box-shadow .22s ease, border-color .22s ease, background .22s ease, color .22s ease, opacity .22s ease;
}

.flip-arrow:hover {
  transform: translateY(-2px);
  box-shadow: 0 14px 24px rgba(43, 42, 41, .18);
  border-color: color-mix(in srgb, var(--ink) 24%, transparent);
  background: #fff;
  color: var(--ink);
}

.flip-arrow:active {
  transform: translateY(0);
  box-shadow: 0 6px 12px rgba(43, 42, 41, .14);
}

.flip-arrow:disabled {
  opacity: .32;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

.pdf-pages {
  display: none;
}

@media (max-width: 980px) {
  .viewer-nav {
    top: 12px;
    left: 18px;
    right: 18px;
    padding: 0 8px 0 18px;
    height: 60px;
  }

  .logo-plate { height: 44px; }
  .logo-img { height: 40px; }
  .nav-center { display: none; }
  .nav-call { padding: 10px 20px; }

  .book-host {
    width: calc(100vw - 48px);
  }

  .cover-start {
    width: min(390px, calc(100% - 18px));
  }

  .cover-end {
    width: min(390px, calc(100% - 18px));
  }

  .page-zone {
    width: 18%;
    min-width: 48px;
  }

  .flip-arrow {
    width: 46px;
    height: 54px;
    font-size: 24px;
  }
}

@media (max-width: 560px) {
  .flip-shell {
    padding: 74px 8px 10px;
  }

  .book-host {
    width: calc(100vw - 16px);
  }

  .flip-arrow {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    z-index: 9;
    width: 40px;
    height: 50px;
    font-size: 21px;
    background: #fff;
  }

  .flip-arrow-left { left: 0; }
  .flip-arrow-right { right: 0; }

  .flip-arrow:hover {
    transform: translateY(-50%);
  }

  .cover-start {
    width: min(330px, calc(100% - 14px));
  }

  .cover-end {
    width: min(330px, calc(100% - 14px));
  }

  .page-zone {
    width: 22%;
    min-width: 42px;
  }
}