/* ============================================================
   BLUE WATERS — страница презентации (флипбук)
   Тёмная «читалка» в палитре сайта: каспийская ночь, приливной
   синий, шампанский акцент. Разметка — presentation.html,
   логика — js/presentation.js.
   ============================================================ */

:root {
  --ink:    #0B1E2A;
  --ink-2:  #10293a;
  --tide:   #1D5C7C;
  --tide-l: #2f7fa5;
  --mist:   #9DBECD;
  --gold:   #C0A062;
  --paper:  #F4F6F7;

  --font-d: "Cormorant Garamond", Georgia, serif;
  --font-b: "Manrope", "Segoe UI", system-ui, sans-serif;
}

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

html, body { height: 100%; }

body {
  font-family: var(--font-b);
  background: var(--ink);
  color: var(--paper);
  overflow: hidden;
  -webkit-text-size-adjust: 100%;
}

/* ---------------- читалка ---------------- */

.reader {
  position: fixed;
  inset: 0;
  display: flex;
  flex-direction: column;
  background:
    radial-gradient(1200px 700px at 50% -10%, rgba(29,92,124,.45), transparent 70%),
    linear-gradient(180deg, #0B1E2A 0%, #10293a 55%, #143a4f 100%);
}
.reader:fullscreen,
.reader:-webkit-full-screen { width: 100vw; height: 100vh; }

/* ---- верхняя панель ---- */

.reader__bar {
  position: relative;
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 12px clamp(14px, 3vw, 28px);
  padding-top: max(12px, env(safe-area-inset-top));
  background: rgba(244, 246, 247, .05);
  border-bottom: 1px solid rgba(244, 246, 247, .1);
  backdrop-filter: blur(8px);
  z-index: 20;
}

.reader__title {
  flex: 1 1 auto;
  min-width: 0;
  font-family: var(--font-d);
  font-size: clamp(15px, 1.5vw, 20px);
  font-weight: 500;
  letter-spacing: .12em;
  text-transform: uppercase;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  color: #eaf2f5;
}

.reader__tools { display: flex; gap: 8px; align-items: center; flex: none; }

/* круглые кнопки панели */
.tool {
  width: 36px;
  height: 36px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid rgba(244, 246, 247, .25);
  border-radius: 50%;
  background: transparent;
  color: #eaf2f5;
  font-family: inherit;
  font-size: 15px;
  line-height: 1;
  cursor: pointer;
  text-decoration: none;
  transition: background .18s ease, border-color .18s ease, color .18s ease;
}
.tool:hover { background: rgba(29, 92, 124, .55); border-color: transparent; }

/* «На сайт» и «Скачать PDF» — таблетки с подписью */
.tool--back,
.tool--download {
  width: auto;
  height: 36px;
  padding: 0 16px;
  gap: 8px;
  border-radius: 18px;
  font-size: 12px;
  letter-spacing: .08em;
  white-space: nowrap;
  flex: none;
}
.tool--back { border-color: rgba(192, 160, 98, .45); color: #eadcc0; }
.tool--back:hover { background: rgba(192, 160, 98, .22); border-color: rgba(192, 160, 98, .7); }
.tool--back__icon, .tool--download__icon { font-size: 15px; }

/* переключатель языка */
.langs { display: flex; align-items: center; gap: 6px; flex: none; }
.lang {
  width: 34px;
  height: 34px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  border: 1px solid rgba(244, 246, 247, .22);
  background: transparent;
  color: #cfe0e8;
  font-family: inherit;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: .08em;
  cursor: pointer;
  transition: background .18s ease, color .18s ease, border-color .18s ease;
}
.lang:hover { border-color: var(--tide-l); color: #fff; }
.lang--active { background: var(--tide); border-color: var(--tide); color: #fff; }

/* счётчик страниц — по центру панели */
.reader__pages {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  align-items: baseline;
  justify-content: center;
  gap: 4px;
  pointer-events: none;
}
.reader__pages > * { pointer-events: auto; }
.reader__page-input {
  width: 52px;
  padding: 3px 4px;
  text-align: right;
  font-family: var(--font-b);
  font-size: 13px;
  letter-spacing: .08em;
  color: #fff;
  background: transparent;
  border: none;
  border-bottom: 1px solid rgba(244, 246, 247, .35);
  outline: none;
  transition: border-color .18s ease, background .18s ease;
}
.reader__page-input:hover { border-color: rgba(244, 246, 247, .6); }
.reader__page-input:focus { border-color: var(--tide-l); background: rgba(244, 246, 247, .08); }
.reader__page-suffix {
  font-size: 11px;
  letter-spacing: .16em;
  color: var(--mist);
  white-space: nowrap;
}

/* ---- сцена с книгой ---- */

.reader__stage {
  position: relative;
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 20px 10px;
  padding-bottom: max(20px, env(safe-area-inset-bottom));
  overflow: hidden;
  min-height: 0;
}

.reader__zoom {
  height: 100%;
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  min-width: 0;
}
.reader__zoom--zoomed { overflow: auto; }
.reader__zoom--zoomed .bookwrap { transform-origin: top left; }

.bookwrap {
  display: flex;
  align-items: center;
  transition: transform .2s ease;
  transform-origin: center center;
}

/* корешок слева: краешек предыдущей страницы, как в раскрытом журнале */
.book-spine {
  display: none;
  flex: none;
  position: relative;
  background-color: #efece4;
  background-size: cover;
  background-position: right center;
  background-repeat: no-repeat;
  border-radius: 3px 0 0 3px;
  box-shadow: -3px 4px 14px rgba(0, 0, 0, .32);
  overflow: hidden;
}
.book-spine::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg,
    rgba(0,0,0,.04) 0%, rgba(0,0,0,0) 30%, rgba(0,0,0,.10) 78%, rgba(0,0,0,.32) 100%);
}
.book-spine::before {
  content: "";
  position: absolute;
  left: 0; top: 2px; bottom: 2px;
  width: 4px;
  background: repeating-linear-gradient(90deg,
    rgba(255,255,255,.65) 0 1px, rgba(0,0,0,.10) 1px 2px);
  z-index: 1;
}
.book-spine:not(.book-spine--filled) { background-color: #e6e2d8; }
.book-spine:not(.book-spine--filled)::after {
  background: linear-gradient(90deg, rgba(0,0,0,.02) 0%, rgba(0,0,0,.14) 100%);
}

.flipbook .stf__parent { margin: 0 auto; }
.flipbook .page-el { overflow: hidden; background: #fff; }
.flipbook .page-el img {
  width: 100%;
  height: 100%;
  display: block;
  object-fit: fill;
  -webkit-user-drag: none;
  user-select: none;
}
.flipbook img {
  box-shadow: 0 0 0 1px rgba(0, 0, 0, .12);
  background: #fff;
}

/* анимация открытия — книга разворачивается от корешка */
@keyframes bookOpen {
  0%   { opacity: 0; transform: perspective(1400px) rotateY(-26deg) translateX(24px) scale(.94); }
  60%  { opacity: 1; }
  100% { opacity: 1; transform: perspective(1400px) rotateY(0deg) translateX(0) scale(1); }
}
.bookwrap--enter {
  transform-origin: left center;
  animation: bookOpen .75s cubic-bezier(.22,.8,.3,1) both;
}

/* стрелки листания */
.reader__arrow {
  flex: none;
  width: 52px;
  height: 52px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid rgba(244, 246, 247, .25);
  border-radius: 50%;
  background: transparent;
  color: rgba(234, 242, 245, .85);
  font-size: 26px;
  line-height: 1;
  padding-bottom: 2px;
  cursor: pointer;
  z-index: 5;
  transition: background .18s ease, transform .18s ease;
}
.reader__arrow:hover { background: rgba(29, 92, 124, .55); transform: scale(1.08); }
.reader__arrow:disabled { opacity: .2; cursor: default; transform: none; background: transparent; }

.tool:focus-visible,
.lang:focus-visible,
.reader__arrow:focus-visible { outline: 2px solid var(--gold); outline-offset: 3px; }

/* ---- загрузка ---- */

.reader__loading {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 18px;
  background: inherit;
  z-index: 10;
  color: var(--mist);
}
.reader__loading[hidden] { display: none; }

.reader__loading-wave {
  width: 120px;
  height: 30px;
  animation: bob 1.4s ease-in-out infinite;
}
@keyframes bob {
  0%, 100% { transform: translateY(0); }
  50%      { transform: translateY(-8px); }
}

.reader__loading-text {
  font-size: 11px;
  letter-spacing: .22em;
  text-transform: uppercase;
  color: var(--mist);
  text-align: center;
  padding: 0 20px;
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}

/* ---------------- мобильные ---------------- */

@media (max-width: 900px) {
  .reader__title { display: none; }
  .reader__bar { gap: 10px; justify-content: space-between; }
  .tool--download__text { display: none; }
  .tool--download { width: 36px; padding: 0; border-radius: 50%; }
}

@media (max-width: 640px) {
  .reader__bar { padding-left: 10px; padding-right: 10px; gap: 6px; }
  .reader__pages { position: static; transform: none; flex: 1 1 auto; }
  .reader__page-input { width: 38px; font-size: 12px; }
  .reader__page-suffix { font-size: 10px; letter-spacing: .08em; }
  .tool--back__text { display: none; }
  .tool--back { width: 32px; padding: 0; border-radius: 50%; }
  .lang { width: 29px; height: 29px; font-size: 10px; }
  .langs { gap: 4px; }
  .tool { width: 32px; height: 32px; font-size: 14px; }
  .tool--download { width: 32px; height: 32px; }
  /* масштаб на телефоне даёт сам браузер (щипок) — кнопки не нужны */
  #zoomIn, #zoomOut { display: none; }

  /* стрелки поверх страницы: слайд получает всю ширину экрана */
  .reader__stage { padding: 10px 6px; gap: 0; }
  .reader__arrow {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 38px;
    height: 38px;
    font-size: 20px;
    background: rgba(11, 30, 42, .55);
    border-color: rgba(244, 246, 247, .3);
    backdrop-filter: blur(4px);
  }
  .reader__arrow--left  { left: 6px; }
  .reader__arrow--right { right: 6px; }
  .reader__arrow:hover { transform: translateY(-50%); }
}