:root {
  --bg: #0f1117;
  --bg2: #161b25;
  --bg3: #1e2535;
  --bg4: #252d3f;
  --panel: #1a2030;
  --border: #2a3448;
  --green: #4ade80;
  --green2: #22c55e;
  --amber: #fbbf24;
  --blue: #60a5fa;
  --red: #f87171;
  --purple: #a78bfa;
  --cyan: #22d3ee;
  --text: #e2e8f0;
  --text2: #94a3b8;
  --text3: #64748b;
  --code-bg: #0d1117;
  --sidebar-w: 285px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

body {
  font-family: 'Noto Sans KR', 'Segoe UI', sans-serif;
  background: var(--bg);
  color: var(--text);
  display: flex;
  min-height: 100vh;
  font-size: 15px;
  line-height: 1.7;
}

/* ── SIDEBAR ── */
#ll-sidebar {
  width: var(--sidebar-w);
  height: 100vh;
  background: var(--panel);
  border-right: 1px solid var(--border);
  position: fixed;
  top: 0; left: 0;
  overflow-y: auto;
  z-index: 100;
  display: flex;
  flex-direction: column;
}
.ll-logo {
  padding: 18px 18px 14px;
  border-bottom: 1px solid var(--border);
}
.ll-logo-badge {
  display: inline-flex;
  align-items: center;
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px;
  color: var(--green);
  background: rgba(74,222,128,.08);
  border: 1px solid rgba(74,222,128,.18);
  padding: 5px 11px;
  border-radius: 6px;
  margin-bottom: 10px;
}
.ll-logo-badge::before { content: '$ '; color: var(--green2); margin-right: 4px; }
.ll-logo h1 { font-size: 13.5px; color: var(--text); font-weight: 700; line-height: 1.4; }
.ll-logo p { font-size: 11px; color: var(--text3); margin-top: 3px; }

.ll-progress-wrap {
  padding: 12px 18px;
  border-bottom: 1px solid var(--border);
  background: var(--bg2);
}
.ll-progress-label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 10px;
  color: var(--text3);
  margin-bottom: 5px;
  display: flex;
  justify-content: space-between;
}
.ll-progress-bar {
  height: 3px;
  background: var(--border);
  border-radius: 2px;
  overflow: hidden;
}
.ll-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--green2), var(--blue));
  width: 0%;
  transition: width .5s ease;
}

.ll-nav-section { padding: 12px 10px 4px; }
.ll-nav-title {
  font-size: 9.5px;
  font-weight: 700;
  letter-spacing: .14em;
  text-transform: uppercase;
  padding: 0 8px;
  margin-bottom: 5px;
}
.ll-nav-title.g { color: var(--green2); }
.ll-nav-title.b { color: var(--blue); }
.ll-nav-title.a { color: var(--amber); }

.ll-nav-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 6px 9px;
  border-radius: 5px;
  cursor: pointer;
  font-size: 12.5px;
  color: var(--text2);
  transition: all .12s;
  background: none;
  border: none;
  width: 100%;
  text-align: left;
  font-family: inherit;
}
.ll-nav-item:hover { background: var(--bg4); color: var(--text); }
.ll-nav-item.active-g { background: rgba(74,222,128,.1); color: var(--green); }
.ll-nav-item.active-b { background: rgba(96,165,250,.1); color: var(--blue); }
.ll-nav-item.active-a { background: rgba(251,191,36,.1); color: var(--amber); }
.ll-nav-dot {
  width: 5px; height: 5px;
  border-radius: 50%;
  background: var(--border);
  flex-shrink: 0;
  transition: background .12s;
}
.ll-nav-item.active-g .ll-nav-dot { background: var(--green); }
.ll-nav-item.active-b .ll-nav-dot { background: var(--blue); }
.ll-nav-item.active-a .ll-nav-dot { background: var(--amber); }

/* ── MAIN ── */
#ll-main {
  margin-left: var(--sidebar-w);
  flex: 1;
  max-width: 920px;
  padding: 0 44px 100px;
}

/* ── CHAPTER TABS ── */
.ll-tabs {
  display: flex;
  gap: 4px;
  padding: 14px 0;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--bg);
}
.ll-tab {
  font-family: 'JetBrains Mono', monospace;
  font-size: 11.5px;
  padding: 6px 14px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: none;
  color: var(--text3);
  cursor: pointer;
  transition: all .12s;
}
.ll-tab:hover { color: var(--text2); }
.ll-tab.tg { background: rgba(74,222,128,.1); color: var(--green); border-color: rgba(74,222,128,.3); }
.ll-tab.tb { background: rgba(96,165,250,.1); color: var(--blue); border-color: rgba(96,165,250,.3); }
.ll-tab.ta { background: rgba(251,191,36,.1); color: var(--amber); border-color: rgba(251,191,36,.3); }

/* ── CHAPTER HERO ── */
.ll-hero {
  padding: 40px 0 28px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 36px;
}
.ll-badge {
  display: inline-flex;
  align-items: center;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: .1em;
  text-transform: uppercase;
  padding: 4px 12px;
  border-radius: 20px;
  margin-bottom: 14px;
}
.ll-badge.g { background: rgba(74,222,128,.12); color: var(--green); border: 1px solid rgba(74,222,128,.2); }
.ll-badge.b { background: rgba(96,165,250,.12); color: var(--blue); border: 1px solid rgba(96,165,250,.2); }
.ll-badge.a { background: rgba(251,191,36,.12); color: var(--amber); border: 1px solid rgba(251,191,36,.2); }
.ll-hero h2 { font-size: 28px; font-weight: 700; margin-bottom: 10px; line-height: 1.3; }
.ll-hero p { color: var(--text2); max-width: 600px; }

/* ── LESSON ── */
.ll-lesson {
  margin-bottom: 44px;
  padding-bottom: 38px;
  border-bottom: 1px solid var(--border);
}
.ll-lesson:last-child { border-bottom: none; }
.ll-lesson-num {
  font-family: 'JetBrains Mono', monospace;
  font-size: 11px;
  color: var(--text3);
  margin-bottom: 5px;
}
.ll-lesson h3 {
  font-size: 19px;
  font-weight: 700;
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 10px;
}
.ll-icon {
  width: 26px; height: 26px;
  border-radius: 6px;
  display: flex; align-items: center; justify-content: center;
  font-size: 13px; flex-shrink: 0;
}
.ll-icon.g { background: rgba(74,222,128,.15); }
.ll-icon.b { background: rgba(96,165,250,.15); }
.ll-icon.a { background: rgba(251,191,36,.15); }

.ll-lesson p { color: var(--text2); margin-bottom: 12px; line-height: 1.8; }
.ll-lesson ul, .ll-lesson ol { color: var(--text2); padding-left: 22px; margin-bottom: 12px; }
.ll-lesson li { margin-bottom: 5px; line-height: 1.75; }
.ll-lesson strong { color: var(--text); font-weight: 600; }
.ll-lesson h4 { font-size: 15px; color: var(--text); margin: 18px 0 8px; font-weight: 600; }
.ll-lesson code {
  font-family: 'JetBrains Mono', monospace;
  font-size: 12.5px;
  background: rgba(34,211,238,.08);
  color: var(--cyan);
  padding: 2px 6px;
  border-radius: 4px;
}

/* ── CODE BLOCK ── */
.ll-code {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  margin: 14px 0;
  overflow: hidden;
}
.ll-code-hdr {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 7px 14px;
  background: var(--bg3);
  border-bottom: 1px solid var(--border);
}
.ll-code-hdr .ll-dots { display: flex; gap: 5px; }
.ll-code-hdr .ll-dot { width: 10px; height: 10px; border-radius: 50%; }
.dot-r { background: #ff5f57; }
.dot-y { background: #febc2e; }
.dot-g2 { background: #28c840; }
.ll-code-lang { font-family: 'JetBrains Mono', monospace; font-size: 10.5px; color: var(--text3); }
.ll-copy-btn {
  font-family: 'JetBrains Mono', monospace;
  font-size: 10px;
  color: var(--text3);
  background: none;
  border: 1px solid var(--border);
  padding: 2px 8px;
  border-radius: 4px;
  cursor: pointer;
  transition: all .12s;
}
.ll-copy-btn:hover { color: var(--text2); border-color: var(--text3); }

.ll-code pre {
  padding: 18px 20px;
  overflow-x: auto;
  font-family: 'JetBrains Mono', monospace;
  font-size: 13px;
  line-height: 1.7;
  color: var(--text);
}
.kw { color: #c792ea; }
.fn { color: #82aaff; }
.str { color: #c3e88d; }
.cm { color: #546e7a; font-style: italic; }
.num { color: #f78c6c; }
.op { color: var(--cyan); }
.type { color: #80cbc4; }
.pre { color: #ffcb6b; }
.prompt { color: var(--green2); user-select: none; }
.out { color: var(--text3); }
.hl { background: rgba(74,222,128,.07); display: block; margin: 0 -20px; padding: 0 20px; }

/* ── TERMINAL ── */
.ll-term {
  background: #080c14;
  border: 1px solid var(--border);
  border-radius: 10px;
  margin: 14px 0;
  overflow: hidden;
}
.ll-term-bar {
  background: var(--bg3);
  padding: 7px 14px;
  display: flex;
  align-items: center;
  gap: 10px;
  border-bottom: 1px solid var(--border);
}
.ll-term-title {
  font-family: 'JetBrains Mono', monospace;
  font-size: 10.5px;
  color: var(--text3);
  flex: 1;
  text-align: center;
}
.ll-term pre {
  padding: 14px 18px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 12.5px;
  line-height: 1.75;
  color: var(--text);
}

/* ── INFO BOXES ── */
.ll-box {
  border-radius: 8px;
  padding: 13px 16px;
  margin: 14px 0;
  display: flex;
  gap: 11px;
  font-size: 13.5px;
  line-height: 1.7;
}
.ll-box.tip { background: rgba(74,222,128,.06); border: 1px solid rgba(74,222,128,.18); }
.ll-box.warn { background: rgba(251,191,36,.06); border: 1px solid rgba(251,191,36,.18); }
.ll-box.info { background: rgba(96,165,250,.06); border: 1px solid rgba(96,165,250,.18); }
.ll-box.danger { background: rgba(248,113,113,.06); border: 1px solid rgba(248,113,113,.18); }
.ll-box-icon { font-size: 15px; margin-top: 1px; flex-shrink: 0; }
.ll-box-body { color: var(--text2); }
.ll-box-body strong { color: var(--text); }

/* ── CMD TABLE ── */
.ll-table {
  width: 100%;
  border-collapse: collapse;
  margin: 14px 0;
  font-size: 13px;
}
.ll-table th {
  background: var(--bg3);
  color: var(--text3);
  font-weight: 600;
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: .09em;
  padding: 9px 13px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}
.ll-table td {
  padding: 9px 13px;
  border-bottom: 1px solid rgba(42,52,72,.5);
  color: var(--text2);
  vertical-align: top;
}
.ll-table tr:hover td { background: var(--bg3); }
.ll-table code {
  font-family: 'JetBrains Mono', monospace;
  color: var(--cyan);
  background: rgba(34,211,238,.08);
  padding: 1px 6px;
  border-radius: 4px;
  font-size: 12px;
}
.ll-table .ex { color: var(--green2); font-family: 'JetBrains Mono', monospace; font-size: 11.5px; }

/* ── FILE TREE ── */
.ll-tree {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px 18px;
  margin: 12px 0;
  font-family: 'JetBrains Mono', monospace;
  font-size: 12.5px;
  line-height: 1.9;
}
.ll-tree .t-dir { color: #82aaff; }
.ll-tree .t-file { color: var(--text2); }
.ll-tree .t-ann { color: var(--text3); }

/* ── QUIZ ── */
.ll-quiz {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 18px;
  margin: 18px 0;
}
.ll-quiz-q {
  font-weight: 600;
  color: var(--text);
  margin-bottom: 13px;
  font-size: 14px;
}
.ll-quiz-q::before { content: '❓ '; }
.ll-quiz-opts { display: flex; flex-direction: column; gap: 7px; }
.ll-quiz-opt {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 9px 13px;
  cursor: pointer;
  font-size: 13px;
  color: var(--text2);
  transition: all .12s;
  font-family: inherit;
  text-align: left;
  width: 100%;
}
.ll-quiz-opt:hover:not(:disabled) { border-color: var(--text3); color: var(--text); }
.ll-quiz-opt.correct { background: rgba(74,222,128,.1); border-color: var(--green); color: var(--green); }
.ll-quiz-opt.wrong { background: rgba(248,113,113,.1); border-color: var(--red); color: var(--red); }
.ll-quiz-result { margin-top: 10px; font-size: 13px; color: var(--text2); display: none; line-height: 1.6; }
.ll-quiz-result.show { display: block; }

/* ── CHAPTER VISIBILITY ── */
.ll-chapter { display: none; }
.ll-chapter.active { display: block; }

/* ── COMPARE GRID ── */
.ll-compare {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin: 14px 0;
}
.ll-compare-box {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
}
.ll-compare-box .ll-compare-hdr {
  padding: 8px 14px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 11px;
  font-weight: 600;
  border-bottom: 1px solid var(--border);
}
.ll-compare-box.py .ll-compare-hdr { color: var(--blue); background: rgba(96,165,250,.07); }
.ll-compare-box.c  .ll-compare-hdr { color: var(--amber); background: rgba(251,191,36,.07); }
.ll-compare-box pre {
  padding: 14px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px;
  line-height: 1.65;
  overflow-x: auto;
}

/* ── TOP BAR (mobile) ── */
#ll-topbar {
  display: none;
  position: fixed;
  top: 0; left: 0; right: 0;
  background: var(--panel);
  border-bottom: 1px solid var(--border);
  padding: 10px 14px;
  z-index: 200;
  align-items: center;
  gap: 10px;
}
#ll-menu-btn {
  background: none;
  border: 1px solid var(--border);
  color: var(--text2);
  padding: 4px 10px;
  border-radius: 5px;
  cursor: pointer;
  font-size: 14px;
}

@media (max-width: 960px) {
  #ll-sidebar { transform: translateX(-100%); transition: transform .25s; box-shadow: 4px 0 20px rgba(0,0,0,.4); }
  #ll-sidebar.open { transform: translateX(0); }
  #ll-main { margin-left: 0; padding: 20px 18px 80px; }
  #ll-topbar { display: flex; }
  .ll-hero { padding: 60px 0 22px; }
  .ll-hero h2 { font-size: 22px; }
  .ll-compare { grid-template-columns: 1fr; }
}