:root {
  --bg: #fafaf7;
  --bg-elev: #ffffff;
  --bg-side: #f1f0eb;
  --text: #1c1d1b;
  --text-muted: #686b65;
  --text-dim: #989b93;
  --accent: #126b5d;
  --accent-soft: #e5f1ee;
  --accent-strong: #0d4f44;
  --warn: #a84b2a;
  --warn-soft: #fff1e8;
  --crux-bg: #eaf4f1;
  --crux-border: #126b5d;
  --aside-bg: #eeeae1;
  --aside-border: #c8c0ad;
  --tip-bg: #fff8dc;
  --tip-border: #d8c15b;
  --fig-bg: #f4f7f4;
  --fig-border: #d8ddd5;
  --code-bg: #1e211f;
  --code-text: #f1f0e8;
  --code-comment: #9aa39c;
  --rule: #e1dfd7;
  --link: #245c8d;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #181918;
    --bg-elev: #222421;
    --bg-side: #141614;
    --text: #ece9df;
    --text-muted: #aaa69b;
    --text-dim: #747066;
    --accent: #7fd3c3;
    --accent-soft: #18332f;
    --accent-strong: #9ce0d3;
    --warn: #ff9a71;
    --warn-soft: #3c241b;
    --crux-bg: #17302c;
    --crux-border: #7fd3c3;
    --aside-bg: #282722;
    --aside-border: #4a453b;
    --tip-bg: #38310d;
    --tip-border: #8d7a20;
    --fig-bg: #202720;
    --fig-border: #3b443c;
    --code-bg: #0d0f0e;
    --code-text: #e9e6dd;
    --code-comment: #838982;
    --rule: #363733;
    --link: #8bbcff;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.28);
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; min-height: 100%; }
html { scroll-behavior: smooth; }
body {
  font-family: 'Pretendard', 'Noto Sans KR', -apple-system, BlinkMacSystemFont, 'Apple SD Gothic Neo', 'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  word-break: keep-all;
  overflow-wrap: break-word;
}

a { color: var(--link); text-decoration: none; border-bottom: 1px solid color-mix(in srgb, var(--link), transparent 70%); }
a:hover { border-bottom-color: var(--link); }
strong { color: var(--text); }
code {
  background: var(--aside-bg);
  padding: 1px 6px;
  border-radius: 4px;
  font-family: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.88em;
}
pre {
  margin: 18px 0;
  padding: 16px 18px;
  border-radius: 8px;
  background: var(--code-bg);
  color: var(--code-text);
  overflow-x: auto;
  box-shadow: var(--shadow);
  font-family: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 13px;
  line-height: 1.58;
}
pre code { background: none; padding: 0; border-radius: 0; color: inherit; font-size: inherit; }

.layout {
  display: grid;
  grid-template-columns: 310px minmax(0, 1fr);
  min-height: 100vh;
}

.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  min-width: 0;
  overflow-y: auto;
  padding: 20px 0 24px;
  background: var(--bg-side);
  border-right: 1px solid var(--rule);
}

.sidebar-brand {
  padding: 0 20px 16px;
  border-bottom: 1px solid var(--rule);
  margin-bottom: 12px;
}
.sidebar-brand h2 {
  margin: 0 0 4px;
  font-size: 17px;
  font-weight: 800;
  letter-spacing: -0.01em;
}
.sidebar-brand p {
  margin: 0;
  color: var(--text-muted);
  font-size: 12px;
  font-style: italic;
}
.home-link {
  display: inline-flex;
  margin-top: 12px;
  color: var(--accent);
  border: 0;
  font-size: 12px;
  font-weight: 700;
}

.search-wrap { padding: 0 20px 12px; }
#search {
  width: 100%;
  padding: 8px 10px;
  border: 1px solid var(--rule);
  border-radius: 6px;
  background: var(--bg-elev);
  color: var(--text);
  font: inherit;
  font-size: 13px;
}
#search:focus { outline: 2px solid var(--accent); outline-offset: -1px; }

.part-group { margin-bottom: 16px; }
.part-label {
  padding: 8px 20px 4px;
  color: var(--text-dim);
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.lecture-list { list-style: none; margin: 0; padding: 0; }
.lecture-list li.hidden { display: none; }
.lecture-list button {
  width: 100%;
  display: grid;
  grid-template-columns: 36px minmax(0, 1fr);
  gap: 8px;
  align-items: baseline;
  padding: 8px 20px 8px 24px;
  border: 0;
  border-left: 3px solid transparent;
  background: none;
  color: var(--text);
  cursor: pointer;
  font: inherit;
  text-align: left;
  line-height: 1.42;
}
.lecture-list button:hover { background: var(--bg-elev); }
.lecture-list button.active {
  background: var(--bg-elev);
  border-left-color: var(--accent);
  font-weight: 700;
}
.lecture-num {
  color: var(--text-dim);
  font-family: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 11px;
  font-variant-numeric: tabular-nums;
}
.lecture-title {
  min-width: 0;
  font-size: 13.5px;
}
.lecture-speaker {
  grid-column: 2;
  color: var(--text-muted);
  font-size: 11.5px;
  font-weight: 400;
}

.content {
  width: 100%;
  max-width: 900px;
  min-width: 0;
  padding: 56px 64px 96px;
}

.welcome { display: block; }
.welcome h1 {
  margin: 0 0 8px;
  font-size: 36px;
  font-weight: 850;
  line-height: 1.2;
  letter-spacing: -0.02em;
}
.welcome .sub {
  margin: 0 0 32px;
  color: var(--text-muted);
  font-size: 16px;
  font-style: italic;
}
.lead {
  margin: 28px 0;
  padding: 4px 0 4px 18px;
  border-left: 3px solid var(--accent);
  color: var(--text);
  font-size: 17px;
  line-height: 1.82;
}
.welcome p, .welcome li { font-size: 15.5px; }
.welcome ul { padding-left: 22px; }
.welcome li { margin: 6px 0; }

.lecture {
  display: none;
  animation: fadein 0.18s ease-out;
}
.lecture.active { display: block; }
@keyframes fadein {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: none; }
}

.lecture-header {
  padding-bottom: 18px;
  border-bottom: 1px solid var(--rule);
  margin-bottom: 32px;
}
.chapter-num {
  margin-bottom: 6px;
  color: var(--accent);
  font-family: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.09em;
}
.chapter-num::before { content: "Lecture "; }
.lecture-header h1 {
  margin: 0 0 8px;
  font-size: 32px;
  font-weight: 850;
  line-height: 1.24;
  letter-spacing: -0.015em;
  max-width: 100%;
  word-break: normal;
  overflow-wrap: anywhere;
}
.lecture-en {
  margin: 0;
  color: var(--text-muted);
  font-size: 14.5px;
  font-style: italic;
}
.lecture-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 14px;
  margin-top: 12px;
  color: var(--text-muted);
  font-family: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 11.5px;
}
.badge {
  display: inline-flex;
  align-items: center;
  padding: 1px 7px;
  border: 1px solid var(--rule);
  border-radius: 999px;
  background: var(--bg-elev);
  color: var(--text-muted);
}
.badge.high { border-color: color-mix(in srgb, var(--accent), var(--rule) 45%); color: var(--accent-strong); }
.badge.partial { border-color: color-mix(in srgb, var(--warn), var(--rule) 30%); background: var(--warn-soft); color: var(--warn); }

.lecture section { margin: 32px 0; }
.lecture h2 {
  margin: 36px 0 14px;
  font-size: 22px;
  font-weight: 800;
  line-height: 1.36;
  letter-spacing: -0.01em;
}
.lecture h3 {
  margin: 24px 0 10px;
  font-size: 17px;
  font-weight: 800;
}
.lecture p { margin: 12px 0; font-size: 15.5px; }
.lecture ul, .lecture ol { padding-left: 24px; }
.lecture li { margin: 6px 0; font-size: 15.5px; }

.crux, .aside, .tip {
  margin: 22px 0;
  padding: 14px 18px;
  border-left: 4px solid;
  border-radius: 8px;
}
.crux { background: var(--crux-bg); border-color: var(--crux-border); }
.aside { background: var(--aside-bg); border-color: var(--aside-border); }
.tip { background: var(--tip-bg); border-color: var(--tip-border); }
.crux-label, .aside-label, .tip-label {
  margin-bottom: 6px;
  font-size: 11.5px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.crux-label { color: var(--accent); }
.aside-label { color: var(--text-muted); }
.tip-label { color: #8b6d08; }
@media (prefers-color-scheme: dark) {
  .tip-label { color: #e3c95a; }
}
.crux p, .aside p, .tip p { margin: 4px 0; font-size: 14.5px; }

.figure {
  margin: 22px 0;
  padding: 15px 16px 16px;
  border: 1px solid var(--fig-border);
  border-radius: 8px;
  background: var(--fig-bg);
}
.fig-label {
  margin-bottom: 12px;
  color: var(--text-muted);
  font-family: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.fig-note {
  margin-top: 10px;
  color: var(--text-muted);
  font-size: 13px;
}

.timeline { display: grid; gap: 10px; font-family: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 12px; }
.timeline-row { display: grid; grid-template-columns: 86px minmax(0, 1fr) 84px; gap: 10px; align-items: center; }
.timeline-name { color: var(--text-muted); }
.track { position: relative; height: 30px; background: var(--bg-elev); border: 1px solid var(--rule); border-radius: 5px; overflow: hidden; }
.seg {
  position: absolute;
  top: 4px;
  height: 20px;
  display: grid;
  place-items: center;
  border-radius: 4px;
  color: #fff;
  font-size: 10px;
  font-weight: 800;
  white-space: nowrap;
}
.seg.launch { background: var(--warn); }
.seg.kernel { background: var(--accent); }
.seg.idle { background: var(--aside-border); color: var(--text); }
.reading { color: var(--text); font-weight: 800; text-align: right; }
.reading.bad { color: var(--warn); }
.reading.good { color: var(--accent-strong); }

.ladder { display: grid; gap: 8px; }
.ladder-step {
  display: grid;
  grid-template-columns: 130px minmax(0, 1fr);
  gap: 12px;
  align-items: baseline;
  padding: 12px 14px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: var(--bg-elev);
}
.ladder-step b { color: var(--accent); font-family: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 12px; }
.ladder-step span { color: var(--text-muted); font-size: 14px; }

.flow {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 7px;
  align-items: stretch;
}
.flow-step {
  position: relative;
  min-height: 82px;
  padding: 12px 10px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: var(--bg-elev);
}
.flow-step::after {
  content: ">";
  position: absolute;
  top: 50%;
  right: -10px;
  transform: translateY(-50%);
  color: var(--accent);
  font-family: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-weight: 800;
}
.flow-step:last-child::after { content: ""; }
.flow-step b { display: block; color: var(--text); font-size: 13px; line-height: 1.35; }
.flow-step span { display: block; margin-top: 5px; color: var(--text-muted); font-size: 12px; line-height: 1.45; }

.grid-viz {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  align-items: center;
}
.block-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 6px;
}
.block {
  min-height: 54px;
  display: grid;
  place-items: center;
  border: 1px solid var(--rule);
  border-radius: 7px;
  background: var(--bg-elev);
  color: var(--text-muted);
  font-family: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 11px;
  font-weight: 700;
}
.block.hot { background: var(--accent-soft); color: var(--accent-strong); border-color: color-mix(in srgb, var(--accent), var(--rule) 45%); }
.threads {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  gap: 4px;
}
.thread {
  aspect-ratio: 1;
  display: grid;
  place-items: center;
  border-radius: 4px;
  background: var(--accent);
  color: #fff;
  font-family: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 9px;
  font-weight: 800;
}
.thread.dim { background: var(--aside-border); color: var(--text); }

.memory-bars { display: grid; gap: 8px; font-family: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 12px; }
.memory-row { display: grid; grid-template-columns: 118px minmax(0, 1fr) 92px; gap: 10px; align-items: center; }
.bar-label { color: var(--text-muted); }
.bar-wrap { height: 18px; background: var(--bg-elev); border: 1px solid var(--rule); border-radius: 4px; overflow: hidden; }
.bar-fill { height: 100%; background: var(--accent); border-radius: 3px; }
.bar-fill.warn { background: var(--warn); }
.bar-fill.soft { background: var(--aside-border); }
.bar-value { color: var(--text); font-weight: 800; text-align: right; }

.key-table {
  display: grid;
  border: 1px solid var(--rule);
  border-radius: 8px;
  overflow: hidden;
}
.key-row {
  display: grid;
  grid-template-columns: 135px minmax(0, 1fr);
  gap: 14px;
  padding: 10px 14px;
  background: var(--bg-elev);
  border-bottom: 1px solid var(--rule);
}
.key-row:last-child { border-bottom: 0; }
.key-row b { color: var(--accent); font-family: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 12px; }
.key-row span { color: var(--text-muted); font-size: 14px; }

.source-links {
  margin-top: 40px;
  padding: 16px 18px;
  border-radius: 8px;
  background: var(--aside-bg);
  color: var(--text-muted);
  font-size: 13px;
}
.source-links h3 { margin: 0 0 8px; color: var(--text); font-size: 15px; }
.source-links ul { margin: 0; padding-left: 20px; }
.source-links li { margin: 4px 0; font-size: 13px; }
.source-links .muted { color: var(--text-muted); }

.chapter-nav {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-top: 56px;
  padding-top: 24px;
  border-top: 1px solid var(--rule);
}
.chapter-nav button {
  flex: 1;
  min-height: 66px;
  padding: 12px 16px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: var(--bg-elev);
  color: var(--text);
  cursor: pointer;
  font: inherit;
  font-size: 13.5px;
  line-height: 1.4;
  text-align: left;
  transition: background 0.12s, border-color 0.12s;
}
.chapter-nav button:hover:not(:disabled) { background: var(--accent-soft); border-color: var(--accent); }
.chapter-nav button:disabled { opacity: 0.45; cursor: not-allowed; }
.chapter-nav .nav-label {
  display: block;
  margin-bottom: 2px;
  color: var(--text-muted);
  font-size: 11px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.chapter-nav button.next { text-align: right; }

.footer-note {
  margin-top: 48px;
  padding: 20px;
  border-radius: 8px;
  background: var(--aside-bg);
  color: var(--text-muted);
  font-size: 12.5px;
  line-height: 1.6;
}
.footer-note strong { color: var(--text); }

@media (max-width: 920px) {
  .flow { grid-template-columns: 1fr; }
  .flow-step::after { content: "v"; top: auto; right: 50%; bottom: -17px; transform: translateX(50%); }
  .flow-step:last-child::after { content: ""; }
  .grid-viz { grid-template-columns: 1fr; }
}

@media (max-width: 860px) {
  .layout { grid-template-columns: 1fr; }
  .sidebar {
    position: static;
    height: auto;
    max-height: 52vh;
    border-right: 0;
    border-bottom: 1px solid var(--rule);
  }
  .content { padding: 32px 22px 64px; }
  .lecture-header h1 { font-size: 26px; }
  .welcome h1 { font-size: 30px; }
  .timeline-row { grid-template-columns: 72px minmax(0, 1fr); }
  .reading { grid-column: 2; text-align: left; }
  .ladder-step, .key-row { grid-template-columns: 1fr; gap: 4px; }
  .memory-row { grid-template-columns: 96px minmax(0, 1fr); }
  .bar-value { grid-column: 2; text-align: left; }
}