/* ===== Google Fonts ===== */
@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+TC:wght@300;400;500;700&family=Noto+Serif+TC:wght@400;600;700&display=swap');

/* ===== CSS Variables ===== */
:root {
  --primary: #1a3a5c;
  --primary-light: #2a5080;
  --primary-dark: #0f2238;
  --accent: #c0392b;
  --bg: #f8f9fa;
  --bg-white: #ffffff;
  --border: #dde3ea;
  --text: #2c3e50;
  --text-light: #5a6a7a;
  --sidebar-width: 260px;
  --header-height: 60px;
  --highlight-bg: #fff176;
  --highlight-current: #ffb300;
  --chapter-bg: #eaf0f8;
  --chapter-border: #1a3a5c;
  --font-sans: 'Noto Sans TC', 'Microsoft JhengHei', sans-serif;
  --font-serif: 'Noto Serif TC', 'PMingLiU', serif;
  --shadow-sm: 0 1px 4px rgba(0,0,0,0.08);
  --shadow-md: 0 2px 12px rgba(0,0,0,0.12);
  --radius: 6px;
  --transition: 0.2s ease;
}

/* ===== Reset & Base ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; font-size: 16px; }

body {
  font-family: var(--font-sans);
  color: var(--text);
  background: var(--bg);
  line-height: 1.8;
  overflow-x: hidden;
}

/* ===== Header ===== */
#site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: var(--primary);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 20px;
  z-index: 1000;
  box-shadow: var(--shadow-md);
  gap: 16px;
}

#site-title {
  font-family: var(--font-serif);
  font-size: 1rem;
  font-weight: 700;
  white-space: nowrap;
  letter-spacing: 0.03em;
  flex-shrink: 0;
}

#header-controls {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: 1;
  justify-content: flex-end;
}

#search-wrapper {
  position: relative;
  display: flex;
  align-items: center;
}

#search-input {
  font-family: var(--font-sans);
  font-size: 0.875rem;
  padding: 6px 36px 6px 12px;
  border: 1px solid rgba(255,255,255,0.3);
  border-radius: 20px;
  background: rgba(255,255,255,0.15);
  color: #fff;
  outline: none;
  width: 220px;
  transition: all var(--transition);
}

#search-input::placeholder { color: rgba(255,255,255,0.6); }
#search-input:focus {
  background: rgba(255,255,255,0.25);
  border-color: rgba(255,255,255,0.6);
  width: 260px;
}

#search-clear {
  position: absolute;
  right: 8px;
  background: none;
  border: none;
  color: rgba(255,255,255,0.7);
  cursor: pointer;
  font-size: 1rem;
  line-height: 1;
  display: none;
  padding: 2px;
}
#search-clear:hover { color: #fff; }

#search-count {
  font-size: 0.8rem;
  color: rgba(255,255,255,0.8);
  white-space: nowrap;
  min-width: 60px;
}

#btn-print {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  padding: 5px 14px;
  border: 1px solid rgba(255,255,255,0.5);
  border-radius: 4px;
  background: transparent;
  color: #fff;
  cursor: pointer;
  white-space: nowrap;
  transition: all var(--transition);
}
#btn-print:hover { background: rgba(255,255,255,0.15); }

#btn-menu {
  display: none;
  background: none;
  border: none;
  color: #fff;
  font-size: 1.4rem;
  cursor: pointer;
  padding: 4px;
  flex-shrink: 0;
}

/* ===== Layout ===== */
#layout {
  display: flex;
  padding-top: var(--header-height);
  min-height: 100vh;
}

/* ===== Sidebar ===== */
#sidebar {
  position: fixed;
  top: var(--header-height);
  left: 0;
  bottom: 0;
  width: var(--sidebar-width);
  background: var(--bg-white);
  border-right: 1px solid var(--border);
  overflow-y: auto;
  z-index: 900;
  transition: transform var(--transition);
}

#sidebar-inner {
  padding: 16px 0 40px;
}

#sidebar h2 {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-light);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 0 18px 10px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 8px;
}

#toc-list {
  list-style: none;
}

#toc-list li a {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 9px 18px;
  font-size: 0.875rem;
  color: var(--text);
  text-decoration: none;
  transition: all var(--transition);
  border-left: 3px solid transparent;
}

#toc-list li a:hover {
  background: var(--chapter-bg);
  color: var(--primary);
}

#toc-list li a.active {
  background: var(--chapter-bg);
  color: var(--primary);
  border-left-color: var(--primary);
  font-weight: 700;
}

/* Screen-reader only utility */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

.toc-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--primary);
  color: #fff;
  font-size: 0.75rem;
  font-weight: 700;
  flex-shrink: 0;
}

#toc-list li a.active .toc-num { background: var(--primary-dark); }
#toc-list li a:hover .toc-num { background: var(--primary-light); }

/* ===== Overlay for mobile ===== */
#sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.4);
  z-index: 850;
}

/* ===== Main Content ===== */
#main {
  margin-left: var(--sidebar-width);
  flex: 1;
  min-width: 0;
  padding: 36px 48px 80px;
  max-width: 900px;
}

/* ===== Document Header ===== */
#doc-header {
  text-align: center;
  margin-bottom: 40px;
  padding-bottom: 28px;
  border-bottom: 2px solid var(--primary);
}

#doc-header h1 {
  font-family: var(--font-serif);
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--primary);
  line-height: 1.4;
  margin-bottom: 12px;
}

#doc-preamble {
  font-family: var(--font-serif);
  font-size: 0.95rem;
  color: var(--text-light);
  line-height: 1.9;
  max-width: 640px;
  margin: 0 auto;
  font-style: italic;
}

/* ===== Chapters & Articles ===== */
.chapter {
  margin-bottom: 40px;
}

.chapter-header {
  display: flex;
  align-items: center;
  gap: 12px;
  background: var(--chapter-bg);
  border-left: 4px solid var(--chapter-border);
  padding: 12px 20px;
  border-radius: 0 var(--radius) var(--radius) 0;
  margin-bottom: 20px;
}

.chapter-number {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--bg-white);
  background: var(--primary);
  padding: 3px 10px;
  border-radius: 12px;
  white-space: nowrap;
}

.chapter-title {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--primary);
}

.article {
  padding: 18px 24px;
  margin-bottom: 12px;
  background: var(--bg-white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition);
  scroll-margin-top: calc(var(--header-height) + 20px);
}

.article:hover { box-shadow: var(--shadow-md); }

.article-header {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 10px;
}

.article-number {
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--primary);
  white-space: nowrap;
  flex-shrink: 0;
}

.article-title-label {
  font-family: var(--font-sans);
  font-size: 0.82rem;
  color: var(--text-light);
  background: var(--chapter-bg);
  padding: 2px 8px;
  border-radius: 10px;
}

.article-content {
  font-family: var(--font-serif);
  font-size: 0.97rem;
  color: var(--text);
  line-height: 2;
  white-space: pre-wrap;
}

/* ===== Highlights ===== */
mark {
  background: var(--highlight-bg);
  color: inherit;
  border-radius: 2px;
  padding: 0 1px;
}

mark.current {
  background: var(--highlight-current);
}

/* ===== No Results ===== */
#no-results {
  display: none;
  text-align: center;
  padding: 60px 20px;
  color: var(--text-light);
}
#no-results .icon { font-size: 3rem; margin-bottom: 12px; }
#no-results p { font-size: 1rem; }

/* ===== Footer ===== */
#site-footer {
  margin-left: var(--sidebar-width);
  background: var(--primary-dark);
  color: rgba(255,255,255,0.75);
  padding: 24px 48px;
  font-size: 0.82rem;
  line-height: 1.8;
}

#site-footer strong { color: #fff; }
#site-footer a { color: rgba(255,255,255,0.8); }

/* ===== Scroll to Top ===== */
#btn-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: var(--primary);
  color: #fff;
  border: none;
  font-size: 1.2rem;
  cursor: pointer;
  box-shadow: var(--shadow-md);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 800;
  transition: background var(--transition), transform var(--transition);
}
#btn-top:hover { background: var(--primary-light); transform: translateY(-2px); }
#btn-top.visible { display: flex; }

/* ===== Responsive ===== */
@media (max-width: 900px) {
  #main { padding: 24px 24px 60px; }
  #doc-header h1 { font-size: 1.4rem; }
}

@media (max-width: 768px) {
  #btn-menu { display: block; }

  #site-title { font-size: 0.9rem; }

  #search-input { width: 140px; }
  #search-input:focus { width: 180px; }

  #sidebar {
    transform: translateX(-100%);
    box-shadow: var(--shadow-md);
  }
  #sidebar.open { transform: translateX(0); }

  #sidebar-overlay.show { display: block; }

  #main { margin-left: 0; padding: 20px 16px 60px; }

  #site-footer { margin-left: 0; padding: 20px 16px; }

  .article { padding: 14px 16px; }

  #btn-top { bottom: 16px; right: 16px; }
}

@media (max-width: 480px) {
  #search-count { display: none; }
  #btn-print { display: none; }
}

/* ===== Print Styles ===== */
@media print {
  #site-header,
  #sidebar,
  #sidebar-overlay,
  #btn-top,
  #btn-menu { display: none !important; }

  #layout { padding-top: 0; }
  #main { margin-left: 0; padding: 0; max-width: 100%; }
  #site-footer { margin-left: 0; }

  body { font-size: 10pt; background: #fff; }

  .article {
    break-inside: avoid;
    border: 1px solid #ccc;
    box-shadow: none;
    margin-bottom: 8pt;
  }

  .chapter-header { background: #eee; }

  #doc-header { border-bottom: 2px solid #000; }
  #doc-header h1 { font-size: 16pt; color: #000; }

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

  mark { background: #ffff99; }

  @page {
    margin: 2cm;
    size: A4;
  }
}