@import url('https://fonts.googleapis.com/css2?family=DM+Sans:ital,opsz,wght@0,9..40,300;0,9..40,400;0,9..40,500;0,9..40,600;1,9..40,400&family=Source+Serif+4:ital,opsz,wght@0,8..60,400;0,8..60,500;0,8..60,600;1,8..60,400&family=JetBrains+Mono:wght@400;500&display=swap');

:root {
  --bg-primary: #ffffff;
  --bg-secondary: #f7f6f3;
  --bg-tertiary: #efeee9;
  --bg-code: #f4f3ef;
  --text-primary: #1a1a1a;
  --text-secondary: #5c5c5c;
  --text-tertiary: #8c8c8c;
  --border-light: rgba(0,0,0,0.08);
  --border-mid: rgba(0,0,0,0.14);
  --accent-property: #1D9E75;
  --accent-labour: #D85A30;
  --accent-company: #534AB7;
  --accent-admin: #185FA5;
  --accent-interp: #993556;
  --sidebar-w: 280px;
  --header-h: 54px;
  --serif: 'Source Serif 4', Georgia, 'Times New Roman', serif;
  --sans: 'DM Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  --mono: 'JetBrains Mono', monospace;
  --radius: 8px;
  --radius-lg: 12px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.06);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-primary: #1a1a1a;
    --bg-secondary: #222222;
    --bg-tertiary: #171717;
    --bg-code: #2a2a2a;
    --text-primary: #e8e6e3;
    --text-secondary: #a0a0a0;
    --text-tertiary: #6a6a6a;
    --border-light: rgba(255,255,255,0.08);
    --border-mid: rgba(255,255,255,0.14);
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.2);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.3);
  }
}

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

html { font-size: 16px; -webkit-font-smoothing: antialiased; }

body {
  font-family: var(--sans);
  background: var(--bg-tertiary);
  color: var(--text-primary);
  line-height: 1.6;
}

::selection { background: rgba(29,158,117,0.15); }

/* Layout */
.app { display: flex; height: 100vh; overflow: hidden; }

/* Sidebar */
.sidebar {
  width: var(--sidebar-w);
  background: var(--bg-primary);
  border-right: 1px solid var(--border-light);
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  transition: transform 0.25s ease, width 0.25s ease;
  z-index: 20;
}

.sidebar.collapsed { width: 0; transform: translateX(-100%); overflow: hidden; }

.sidebar-header {
  padding: 20px 18px 16px;
  border-bottom: 1px solid var(--border-light);
}

.sidebar-header h1 {
  font-family: var(--serif);
  font-size: 18px;
  font-weight: 600;
  letter-spacing: -0.02em;
}

.sidebar-header p {
  font-size: 12px;
  color: var(--text-tertiary);
  margin-top: 3px;
}

.sidebar-nav {
  flex: 1;
  overflow-y: auto;
  padding: 8px 0;
}

.sidebar-nav::-webkit-scrollbar { width: 4px; }
.sidebar-nav::-webkit-scrollbar-thumb { background: var(--border-mid); border-radius: 4px; }

.paper-btn {
  width: 100%;
  border: none;
  background: transparent;
  padding: 10px 16px;
  text-align: left;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 10px;
  border-left: 3px solid transparent;
  transition: all 0.15s;
  font-family: var(--sans);
  color: var(--text-primary);
}

.paper-btn:hover { background: var(--bg-secondary); }
.paper-btn.active { background: var(--bg-secondary); }

.paper-icon {
  width: 30px;
  height: 30px;
  border-radius: 50%;
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  font-weight: 600;
  flex-shrink: 0;
}

.paper-title { font-size: 13px; font-weight: 500; }
.paper-progress { font-size: 11px; color: var(--text-tertiary); margin-top: 1px; }
.pct-label { font-size: 11px; color: var(--text-tertiary); flex-shrink: 0; }
.paper-progress-bar {
  height: 2px;
  background: var(--border-light);
  border-radius: 2px;
  margin-top: 4px;
  overflow: hidden;
}
.paper-progress-fill { height: 100%; border-radius: 2px; transition: width 0.3s ease; }

/* Unit headers in sidebar */
.unit-header {
  width: 100%;
  padding: 6px 16px 6px 46px;
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-tertiary);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 5px;
  transition: all 0.12s;
  user-select: none;
  line-height: 1.4;
}
.unit-header:hover { color: var(--text-secondary); background: var(--bg-secondary); }
.unit-header.active { color: inherit; }
.unit-chevron { font-size: 9px; flex-shrink: 0; }

.topic-btn {
  width: 100%;
  border: none;
  background: transparent;
  padding: 5px 16px 5px 60px;
  text-align: left;
  cursor: pointer;
  font-size: 12px;
  display: flex;
  align-items: flex-start;
  gap: 6px;
  color: var(--text-secondary);
  font-family: var(--sans);
  transition: all 0.12s;
  line-height: 1.45;
}

.topic-btn:hover { color: var(--text-primary); background: var(--bg-secondary); }
.topic-btn.active { font-weight: 500; }
.topic-btn .check { font-size: 10px; flex-shrink: 0; width: 14px; margin-top: 2px; }
.topic-btn .check.done { color: var(--accent-property); }
.topic-label { overflow: hidden; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; }

.sidebar-footer {
  padding: 12px 16px;
  border-top: 1px solid var(--border-light);
  font-size: 11px;
  color: var(--text-tertiary);
}

/* Main */
.main { flex: 1; display: flex; flex-direction: column; min-width: 0; }

.topbar {
  height: var(--header-h);
  padding: 0 20px;
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  gap: 12px;
  background: var(--bg-primary);
  flex-shrink: 0;
}

.menu-btn {
  border: none;
  background: none;
  cursor: pointer;
  font-size: 20px;
  padding: 4px 8px;
  color: var(--text-secondary);
  border-radius: 4px;
}
.menu-btn:hover { background: var(--bg-secondary); }

.search-box {
  flex: 1;
  max-width: 420px;
  position: relative;
}

.search-box input {
  width: 100%;
  padding: 7px 12px 7px 34px;
  border: 1px solid var(--border-light);
  border-radius: var(--radius);
  font-size: 13px;
  font-family: var(--sans);
  background: var(--bg-secondary);
  color: var(--text-primary);
  transition: border-color 0.15s;
}

.search-box input:focus { outline: none; border-color: var(--border-mid); }
.search-box::before {
  content: "\1F50D";
  position: absolute;
  left: 10px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 13px;
  opacity: 0.4;
}

.nav-btns { display: flex; gap: 6px; }
.nav-btn {
  border: 1px solid var(--border-light);
  background: var(--bg-primary);
  border-radius: var(--radius);
  padding: 5px 12px;
  cursor: pointer;
  font-size: 12px;
  font-family: var(--sans);
  color: var(--text-secondary);
  transition: all 0.12s;
}
.nav-btn:hover { background: var(--bg-secondary); border-color: var(--border-mid); }

/* Content */
.content-scroll {
  flex: 1;
  overflow-y: auto;
  padding: 36px 0;
}

.content-scroll::-webkit-scrollbar { width: 6px; }
.content-scroll::-webkit-scrollbar-thumb { background: var(--border-mid); border-radius: 6px; }

.content {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 40px;
}

.content-tags { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 10px; }
.tag {
  font-size: 11px;
  padding: 2px 10px;
  border-radius: 4px;
  font-weight: 500;
  font-family: var(--sans);
}

.content h1 {
  font-family: var(--serif);
  font-size: 26px;
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: -0.02em;
  margin-bottom: 24px;
}

.content-body { font-family: var(--serif); }

.content-body p {
  font-size: 15.5px;
  line-height: 1.85;
  margin-bottom: 16px;
  color: var(--text-primary);
}

.content-body strong { font-weight: 600; }

.content-subhead {
  font-family: var(--sans);
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-tertiary);
  margin: 24px 0 8px;
}

.content-list {
  margin: 0 0 16px 20px;
  font-family: var(--serif);
  font-size: 15.5px;
  line-height: 1.85;
}
.content-list li { margin-bottom: 6px; }

/* Case law highlight */
.case-block {
  margin: 16px 0;
  padding: 12px 16px;
  background: rgba(29,158,117,0.06);
  border-left: 3px solid #1D9E75;
  border-radius: 0 var(--radius) var(--radius) 0;
  font-family: var(--sans);
  font-size: 13.5px;
  line-height: 1.65;
  color: var(--text-primary);
}
.case-label {
  display: inline-block;
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: #1D9E75;
  background: rgba(29,158,117,0.12);
  padding: 1px 6px;
  border-radius: 3px;
  margin-bottom: 5px;
  margin-right: 6px;
}

/* Exam tip highlight */
.tip-block {
  margin: 16px 0;
  padding: 12px 16px;
  background: rgba(234,179,8,0.07);
  border-left: 3px solid #ca8a04;
  border-radius: 0 var(--radius) var(--radius) 0;
  font-family: var(--sans);
  font-size: 13.5px;
  line-height: 1.65;
  color: var(--text-primary);
}
.tip-label {
  display: inline-block;
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: #ca8a04;
  background: rgba(234,179,8,0.15);
  padding: 1px 6px;
  border-radius: 3px;
  margin-bottom: 5px;
  margin-right: 6px;
}

/* Search UI */
.search-clear {
  position: absolute;
  right: 8px;
  top: 50%;
  transform: translateY(-50%);
  border: none;
  background: none;
  cursor: pointer;
  font-size: 13px;
  color: var(--text-tertiary);
  padding: 2px 4px;
}
.search-clear:hover { color: var(--text-primary); }

.search-header {
  margin-bottom: 24px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--border-light);
}
.search-header h2 { font-family: var(--serif); font-size: 22px; font-weight: 600; margin-bottom: 4px; }
.search-header p { font-size: 13px; color: var(--text-tertiary); }

.search-result-card {
  padding: 14px 18px;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  margin-bottom: 10px;
  cursor: pointer;
  background: var(--bg-primary);
  transition: all 0.15s;
}
.search-result-card:hover { border-color: var(--border-mid); box-shadow: var(--shadow-sm); }
.result-paper { font-size: 11px; font-weight: 600; font-family: var(--sans); text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: 4px; }
.result-title { font-size: 14px; font-weight: 500; font-family: var(--sans); margin-bottom: 6px; }
.result-snippet { font-size: 13px; color: var(--text-secondary); line-height: 1.6; font-family: var(--sans); }
.no-results { padding: 40px; text-align: center; color: var(--text-tertiary); font-family: var(--sans); }

/* Unit tag */
.unit-tag {
  background: var(--bg-tertiary) !important;
  color: var(--text-secondary) !important;
}

/* Case law cards */
.cases-section { margin: 28px 0; }
.cases-label {
  font-size: 12px;
  font-weight: 500;
  font-family: var(--sans);
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 12px;
}

.case-card {
  border-left: 3px solid;
  padding: 10px 16px;
  margin-bottom: 10px;
  background: var(--bg-secondary);
  border-radius: 0 var(--radius) var(--radius) 0;
}

.case-name {
  font-size: 14px;
  font-weight: 600;
  font-family: var(--sans);
}

.case-point {
  font-size: 13px;
  color: var(--text-secondary);
  margin-top: 4px;
  line-height: 1.6;
  font-family: var(--sans);
}

/* Media placeholder */
.media-placeholder {
  margin: 32px 0 24px;
  padding: 20px;
  border: 1.5px dashed var(--border-mid);
  border-radius: var(--radius-lg);
  text-align: center;
}

.media-placeholder .title {
  font-size: 14px;
  color: var(--text-secondary);
  font-family: var(--sans);
  font-weight: 500;
}

.media-placeholder .sub {
  font-size: 12px;
  color: var(--text-tertiary);
  margin-top: 4px;
}

/* Audio player */
.audio-section { margin: 28px 0; }
.audio-card-full {
  padding: 16px 18px;
  background: var(--bg-secondary);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-light);
}
.audio-title {
  font-size: 13px;
  font-weight: 500;
  font-family: var(--sans);
  color: var(--text-primary);
  margin-bottom: 2px;
}
.download-btn {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-size: 12px;
  font-family: var(--sans);
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
  border: 1px solid var(--border-light);
  border-radius: var(--radius);
  padding: 5px 12px;
  background: var(--bg-primary);
  transition: all 0.15s;
}
.download-btn:hover {
  background: var(--bg-tertiary);
  border-color: var(--border-mid);
  color: var(--text-primary);
}

/* Infographic section */
.infographic-section { margin: 28px 0; }
.infographic-card {
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 16px;
  background: var(--bg-secondary);
}
.infographic-img {
  width: 100%;
  border-radius: var(--radius);
  display: block;
  cursor: zoom-in;
  transition: transform 0.2s;
  box-shadow: 0 2px 12px rgba(0,0,0,0.08);
}
.infographic-img.infographic-fullscreen {
  position: fixed;
  top: 0; left: 0;
  width: 100vw; height: 100vh;
  object-fit: contain;
  background: rgba(0,0,0,0.92);
  z-index: 9999;
  border-radius: 0;
  cursor: zoom-out;
  padding: 16px;
  box-sizing: border-box;
}
.infographic-hint {
  font-size: 11px;
  color: var(--text-tertiary);
  text-align: center;
  margin: 8px 0 12px;
}

/* Video section */
.video-section { margin: 24px 0; }
.video-card {
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: #000;
  margin-bottom: 12px;
}
.video-card video { width: 100%; display: block; }

/* Footer bar */
.content-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 0;
  border-top: 1px solid var(--border-light);
  margin-top: 20px;
}

.done-btn {
  border: 1px solid var(--border-light);
  background: var(--bg-primary);
  border-radius: var(--radius);
  padding: 8px 18px;
  cursor: pointer;
  font-size: 13px;
  font-family: var(--sans);
  color: var(--text-secondary);
  transition: all 0.15s;
}

.done-btn:hover { background: var(--bg-secondary); }
.done-btn.completed {
  background: rgba(29,158,117,0.08);
  color: var(--accent-property);
  border-color: rgba(29,158,117,0.2);
}

.topic-counter { font-size: 12px; color: var(--text-tertiary); }

/* Mobile */
/* Mobile sidebar backdrop */
.sidebar-backdrop {
  display: none;
}
@media (max-width: 768px) {
  .sidebar-backdrop {
    display: block;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.4);
    z-index: 199;
  }
}

@media (max-width: 768px) {
  /* Sidebar: slide in as overlay */
  .sidebar {
    position: fixed;
    left: 0; top: 0; bottom: 0;
    width: 82vw;
    max-width: 300px;
    z-index: 200;
    box-shadow: 4px 0 24px rgba(0,0,0,0.15);
    transition: transform 0.25s ease;
  }
  .sidebar.collapsed { transform: translateX(-100%); }

  /* Topbar: stack search below menu+nav row on very small screens */
  .topbar {
    flex-wrap: wrap;
    height: auto;
    padding: 8px 12px;
    gap: 8px;
  }
  .search-box {
    order: 3;
    flex: 1 1 100%;
    max-width: 100%;
  }
  .nav-btns { margin-left: auto; }
  .nav-btn { font-size: 12px; padding: 5px 10px; }

  /* Content area */
  .content-scroll { padding: 20px 0 40px; }
  .content { padding: 0 16px; max-width: 100%; }
  .content h1 { font-size: 19px; line-height: 1.35; margin-bottom: 16px; }
  .content-body p { font-size: 14.5px; line-height: 1.8; }
  .content-list { font-size: 14.5px; }
  .content-subhead { font-size: 12px; }

  /* Case & Tip blocks */
  .case-block, .tip-block { font-size: 13px; padding: 10px 12px; }

  /* Tables: scrollable */
  .content-body table {
    display: block;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    font-size: 13px;
  }

  /* Audio section */
  .audio-card-full { padding: 12px; }
  .audio-title { font-size: 13px; }
  audio { width: 100% !important; }

  /* Infographic */
  .infographic-card { padding: 10px; }
  .infographic-img { border-radius: 6px; }

  /* Download button: full width */
  .download-btn {
    display: block;
    text-align: center;
    width: 100%;
    box-sizing: border-box;
  }

  /* Footer: stack */
  .content-footer {
    flex-direction: column;
    gap: 10px;
    align-items: flex-start;
  }
  .done-btn { width: 100%; text-align: center; }

  /* Tags */
  .content-tags { margin-bottom: 8px; }

  /* Search results */
  .search-result-card { padding: 12px 14px; }
  .result-title { font-size: 13px; }
  .result-snippet { font-size: 12px; }

  /* Landing page */
  .landing { padding: 30px 16px; }
  .landing h1 { font-size: 24px; }
  .landing .subtitle { font-size: 14px; margin-bottom: 24px; }
  .paper-cards { grid-template-columns: 1fr 1fr; gap: 10px; }
  .paper-card { padding: 14px; }

  /* Paper selector buttons in sidebar */
  .paper-btn { padding: 10px 12px; }
  .paper-title { font-size: 12px; }

  /* Media placeholder */
  .media-placeholder { padding: 20px 14px; }
}

/* Landing page */
.landing { padding: 60px 40px; max-width: 900px; margin: 0 auto; }
.landing h1 {
  font-family: var(--serif);
  font-size: 36px;
  font-weight: 600;
  letter-spacing: -0.03em;
  margin-bottom: 12px;
}
.landing .subtitle {
  font-size: 16px;
  color: var(--text-secondary);
  margin-bottom: 40px;
  line-height: 1.7;
}

.paper-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 16px; }
.paper-card {
  background: var(--bg-primary);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 20px;
  cursor: pointer;
  transition: all 0.2s;
}
.paper-card:hover { border-color: var(--border-mid); box-shadow: var(--shadow-sm); transform: translateY(-1px); }
.paper-card .num {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 12px;
}
.paper-card .name { font-size: 15px; font-weight: 500; margin-bottom: 4px; }
.paper-card .desc { font-size: 12px; color: var(--text-secondary); line-height: 1.5; }
.paper-card .count { font-size: 11px; color: var(--text-tertiary); margin-top: 10px; }