/* ==========================================================
   CSS 変数
========================================================== */
:root {
  /* カラー */
  --bg:         #0d0d18;
  --bg2:        #13131f;
  --bg3:        #1a1a2e;
  --card:       #16213e;
  --accent:     #6c63ff;
  --accent-b:   #48c6ef;
  --accent2:    #f5576c;
  --grad:       linear-gradient(135deg, #6c63ff 0%, #48c6ef 100%);
  --grad-warm:  linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
  --text:       #f0f0f8;
  --text2:      #9090a8;
  --text3:      #505068;
  --border:     rgba(255,255,255,0.07);
  --glass:      rgba(255,255,255,0.04);
  --shadow:     0 24px 64px rgba(0,0,0,0.55);
  --shadow-sm:  0 4px 16px rgba(0,0,0,0.4);
  --glow:       0 0 28px rgba(108,99,255,0.35);

  /* サイズ */
  --tb-h:  58px;
  --link-h: 56px;
  --bb-h:  56px;
  --bb-btn-size: 44px;
  --bb-icon-size: 20px;
  --bb-gap: 12px;
  --bb-pad-x: 14px;
  --bb-progress-h: 6px;
  --r-sm:  8px;
  --r-md:  14px;
  --r-lg:  22px;

  /* アニメーション */
  --ease:  cubic-bezier(0.4, 0, 0.2, 1);
  --fast:  0.18s;
  --mid:   0.32s;
  --slow:  0.48s;
}

/* ==========================================================
   アプリ骨格
========================================================== */
#app {
  height: 100%;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  position: relative;
}

/* ---- ツールバー ---- */
#toolbar {
  height: var(--tb-h);
  flex-shrink: 0;
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 0 12px;
  background: rgba(13,13,24,0.95);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border-bottom: 1px solid var(--border);
  z-index: 50;
  isolation: isolate;
  transform: translateY(0);
  transition: transform var(--mid) var(--ease),
              opacity  var(--mid) var(--ease);
}

.tb-title-wrap {
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 1px;
}

#tb-title {
  font-size: 0.84rem;
  font-weight: 700;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  color: var(--text);
}

#tb-author {
  font-size: 0.62rem;
  color: var(--text2);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* ---- ビューエリア ---- */
#viewer {
  flex: 1;
  position: relative;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  background:
    radial-gradient(ellipse at 25% 75%,
      rgba(108,99,255,0.06) 0%, transparent 55%),
    radial-gradient(ellipse at 75% 25%,
      rgba(72,198,239,0.05) 0%, transparent 55%),
    var(--bg);
}

#external-link-bar {
  height: var(--link-h);
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0 14px;
  background: rgba(13,13,24,0.78);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

/* ズームコンテナ */
#zoom-container {
  position: absolute;
  inset: 0;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  touch-action: none;
}

#book-stage {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 20px;
  transform-origin: center center;
  will-change: transform;
}

/* ページエリア */
#page-area {
  position: relative;
}

#page-container {
  position: relative;
  will-change: transform;
  border-radius: var(--r-md);
  overflow: hidden;
  box-shadow:
    var(--shadow),
    0 0 0 1px rgba(255,255,255,0.05);
}

/* ---- ボトムバー ---- */
#bottom-bar {
  height: var(--bb-h);
  flex-shrink: 0;
  display: flex;
  align-items: center;
  gap: var(--bb-gap);
  padding: 0 var(--bb-pad-x);
  padding-bottom: env(safe-area-inset-bottom, 0px);
  background: rgba(13,13,24,0.97);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border-top: 1px solid var(--border);
  z-index: 50;
  isolation: isolate;
  transform: translateY(0);
  transition: transform var(--mid) var(--ease),
              opacity  var(--mid) var(--ease);
}

/* ==========================================================
   レスポンシブ
========================================================== */
@media (max-width: 768px) {
  :root {
    --bb-h: 54px;
    --bb-btn-size: 42px;
    --bb-icon-size: 19px;
    --bb-gap: 10px;
    --bb-pad-x: 12px;
    --bb-progress-h: 6px;
  }

  .nav-arrow { display: none !important; }

  #external-link-bar {
    padding: 0 10px;
  }
}

@media (max-width: 480px) {
  :root {
    --bb-h: 50px;
    --bb-btn-size: 38px;
    --bb-icon-size: 17px;
    --bb-gap: 8px;
    --bb-pad-x: 10px;
    --bb-progress-h: 5px;
  }
}

@media (max-width: 380px), (max-height: 720px) and (max-width: 430px) {
  :root {
    --bb-h: 46px;
    --bb-btn-size: 34px;
    --bb-icon-size: 16px;
    --bb-gap: 7px;
    --bb-pad-x: 8px;
    --bb-progress-h: 4px;
  }
}

@media (min-width: 769px) {
  #book-stage { gap: 32px; }
}