/* CSS変数定義: 色やサイズを一括管理します */
:root {
  --primary-color: #3b82f6;
  --primary-hover: #2563eb;
  --bg-color: #f8fafc;
  --panel-bg: #ffffff;
  --text-main: #1e293b;
  --text-muted: #64748b;
  --border-color: #e2e8f0;
  
  --sidebar-width: 280px;
  --header-height: 60px;
  --toolbar-height: 64px;
  --controls-height: 80px;
  
  --transition-speed: 0.2s;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

/* 基本リセット */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Inter', 'Noto Sans JP', sans-serif;
  color: var(--text-main);
  background-color: var(--bg-color);
  line-height: 1.5;
  height: 100vh;
  overflow: hidden; /* 全体スクロールは禁止し、各エリア内でスクロールさせる */
}

a {
  text-decoration: none;
  color: inherit;
}

button {
  cursor: pointer;
  font-family: inherit;
  border: none;
  background: none;
}

/* --- レイアウト構造 --- */
.layout {
  display: flex;
  height: 100vh;
  width: 100vw;
}

/* スマホ用ヘッダー (PCでは非表示) */
.mobile-header {
  display: none;
  height: var(--header-height);
  background: var(--panel-bg);
  border-bottom: 1px solid var(--border-color);
  justify-content: space-between;
  align-items: center;
  padding: 0 1rem;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 50;
  box-shadow: var(--shadow-sm);
}

.menu-toggle {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--text-main);
  font-weight: 500;
  padding: 0.5rem;
  border-radius: 6px;
  transition: background-color var(--transition-speed);
}

.menu-toggle:hover {
  background-color: #f1f5f9;
}

.mobile-title {
  font-weight: 600;
  font-size: 1.1rem;
}

/* --- 左サイドバー --- */
.sidebar {
  width: var(--sidebar-width);
  height: 100vh;
  background-color: var(--panel-bg);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  z-index: 40;
  transition: transform 0.3s ease;
}

.sidebar-header {
  padding: 1.5rem;
  border-bottom: 1px solid var(--border-color);
}

.sidebar-header h2 {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-main);
  line-height: 1.4;
}

.sidebar-nav {
  flex: 1;
  overflow-y: auto;
  padding: 1rem 0;
}

.sidebar-nav ul {
  list-style: none;
}

.menu-item {
  display: block;
  padding: 0.75rem 1.5rem;
  color: var(--text-muted);
  font-weight: 500;
  transition: all var(--transition-speed);
  border-left: 3px solid transparent;
}

.menu-item:hover {
  background-color: #f1f5f9;
  color: var(--text-main);
}

.menu-item.active {
  background-color: #eff6ff;
  color: var(--primary-color);
  border-left-color: var(--primary-color);
  font-weight: 600;
}

.menu-item.indent-1 {
  padding-left: 2.75rem;
  font-size: 0.95rem;
  position: relative;
}

.menu-item.menu-item-external {
  margin-top: 1rem;
  border-top: 1px solid var(--border-color);
  padding-top: 1.25rem;
  font-weight: 500;
  display: flex;
  align-items: center;
  color: var(--primary-color);
}

.menu-item.menu-item-external:hover {
  text-decoration: underline;
  background-color: transparent;
}

.menu-item.indent-1::before {
  content: "";
  position: absolute;
  left: 1.5rem;
  top: 50%;
  width: 0.5rem;
  height: 1px;
  background-color: var(--text-muted);
  opacity: 0.5;
}

.sidebar-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(0, 0, 0, 0.4);
  z-index: 30;
  opacity: 0;
  transition: opacity 0.3s ease;
}

/* --- 右側 ビューワーエリア --- */
.viewer-area {
  flex: 1;
  display: flex;
  flex-direction: column;
  height: 100vh;
  position: relative;
  background: var(--bg-color);
}

/* ツールバー */
.viewer-toolbar {
  height: var(--toolbar-height);
  background: var(--panel-bg);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 2rem;
  box-shadow: var(--shadow-sm);
}

.page-info {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.current-page-title {
  font-size: 1.25rem;
  font-weight: 600;
}

.page-count {
  color: var(--text-muted);
  font-size: 0.95rem;
}

.toolbar-actions {
  display: flex;
  gap: 1rem;
  align-items: center;
}

.btn-tool {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 1rem;
  border-radius: 8px;
  font-weight: 500;
  color: var(--text-main);
  background-color: #f1f5f9;
  transition: all var(--transition-speed);
}

.btn-tool:hover {
  background-color: #e2e8f0;
}

.btn-primary {
  background-color: var(--primary-color);
  color: white;
}

.btn-primary:hover {
  background-color: var(--primary-hover);
}

/* 画像表示領域 */
.image-wrapper {
  flex: 1;
  overflow: auto;
  padding: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}

.image-container {
  max-width: 100%;
  max-height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
  transition: opacity 0.3s;
}

.image-container img {
  max-width: 100%;
  max-height: calc(100vh - var(--toolbar-height) - var(--controls-height) - 4rem);
  object-fit: contain;
  box-shadow: var(--shadow-md);
  background: white; /* 透過PNG対策 */
  border: 1px solid var(--border-color);
}

/* ローディング時の演出 */
.loading {
  opacity: 0.5;
  filter: blur(4px);
}

/* 下部コントロール (前へ 次へ) */
.viewer-controls {
  height: var(--controls-height);
  background: var(--panel-bg);
  border-top: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.5rem;
  padding: 0 2rem;
}

.btn-nav {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 2rem;
  border-radius: 100px; /* 丸みのあるモダンなボタン */
  font-weight: 600;
  font-size: 1rem;
  color: var(--primary-color);
  background-color: #eff6ff;
  border: 2px solid transparent;
  transition: all var(--transition-speed);
}

.btn-nav:hover:not(:disabled) {
  background-color: var(--primary-color);
  color: white;
}

.btn-nav:disabled {
  background-color: #f1f5f9;
  color: #94a3b8;
  cursor: not-allowed;
}

/* --- モーダル（拡大表示） --- */
.zoom-modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background-color: rgba(0, 0, 0, 0.9);
  z-index: 100;
  justify-content: center;
  align-items: center;
}

.zoom-modal.active {
  display: flex;
  flex-direction: column;
  animation: fadeIn 0.2s ease-out;
}

.zoom-toolbar {
  width: 100%;
  padding: 1.5rem;
  display: flex;
  justify-content: flex-end;
  z-index: 101;
  background: linear-gradient(to bottom, rgba(0,0,0,0.8) 0%, rgba(0,0,0,0) 100%);
}

.btn-zoom-out {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: white;
  background: rgba(255, 255, 255, 0.2);
  padding: 0.75rem 1.5rem;
  border-radius: 100px;
  font-size: 1rem;
  font-weight: 600;
  transition: all var(--transition-speed);
  border: 1px solid rgba(255, 255, 255, 0.3);
  backdrop-filter: blur(4px);
}

.btn-zoom-out:hover {
  background: rgba(255, 255, 255, 0.3);
  transform: translateY(-2px);
}

.modal-content {
  width: 95vw;
  height: 95vh;
  overflow: auto; /* 拡大画像用のスクロール */
  display: flex;
  justify-content: center;
  align-items: flex-start;
  padding: 1rem;
}

.modal-content img {
  max-width: none;
  width: auto;
  height: auto;
  cursor: zoom-out;
  box-shadow: 0 0 20px rgba(0,0,0,0.5);
  background: white;
}

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


/* =========================================================
   レスポンシブ (スマホ向け)
   ========================================================= */
@media (max-width: 768px) {
  .mobile-header {
    display: flex; /* ヘッダーを表示 */
  }

  .layout {
    flex-direction: column;
    padding-top: var(--header-height); /* ヘッダー分下げる */
  }

  /* サイドバーを隠して開閉式にする */
  .sidebar {
    position: fixed;
    top: var(--header-height);
    left: 0;
    height: calc(100vh - var(--header-height));
    transform: translateX(-100%); /* 初期は画面外 */
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .sidebar-overlay.open {
    display: block;
    opacity: 1;
  }

  /* ツールバーの簡略化 */
  .viewer-toolbar {
    padding: 0 1rem;
  }
  
  .current-page-title {
    font-size: 1.1rem;
  }

  .tool-label {
    display: none; /* スマホではアイコンのみにする */
  }

  .btn-tool {
    padding: 0.5rem;
  }

  /* 画像表示領域の調整 */
  .image-wrapper {
    padding: 1rem;
  }
  
  .image-container img {
    max-height: calc(100vh - var(--header-height) - var(--toolbar-height) - var(--controls-height) - 2rem);
  }

  /* 下部コントロール */
  .viewer-controls {
    padding: 0 1rem;
    gap: 0.5rem;
  }
  
  .btn-nav {
    padding: 0.75rem 1rem;
    font-size: 0.9rem;
    flex: 1;
    justify-content: center;
  }
}