:root {
  --ink: #111511;
  --muted: #4b574a;
  --paper: #f6f8f2;
  --panel: #ffffff;
  --line: rgba(16, 20, 17, 0.14);
  --green: #55b7e8;
  --green-deep: #1f5f7d;
  --amber: #f5aa3d;
  --shadow: 0 18px 50px rgba(12, 18, 13, 0.12);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: "Malgun Gothic", "맑은 고딕", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.72;
}

a {
  color: inherit;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  justify-content: space-between;
  gap: 16px;
  padding: 14px clamp(18px, 4vw, 48px);
  color: #f7fbf4;
  background: rgba(9, 14, 10, 0.94);
  border-bottom: 1px solid rgba(255, 255, 255, 0.12);
}

.topbar a {
  text-decoration: none;
  font-weight: 800;
}

.hero {
  color: #f7fbf4;
  background:
    linear-gradient(90deg, rgba(9, 14, 10, 0.98), rgba(9, 14, 10, 0.78)),
    #101411;
}

.hero-inner,
.page-grid,
.footer-inner {
  width: min(1180px, calc(100% - 40px));
  margin: 0 auto;
}

.hero-inner {
  padding: 72px 0 54px;
}

.eyebrow {
  margin: 0 0 12px;
  color: var(--green);
  font-size: 13px;
  font-weight: 900;
  text-transform: uppercase;
}

h1 {
  max-width: 880px;
  margin: 0;
  font-size: clamp(38px, 7vw, 72px);
  line-height: 1.04;
}

.lead {
  max-width: 860px;
  margin: 22px 0 0;
  color: rgba(247, 251, 244, 0.82);
  font-size: 19px;
}

.page-grid {
  display: grid;
  grid-template-columns: 250px minmax(0, 1fr);
  gap: 26px;
  padding: 34px 0 80px;
}

.toc {
  position: sticky;
  top: 68px;
  align-self: start;
  padding: 16px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 0;
}

.toc strong {
  display: block;
  margin-bottom: 10px;
}

.toc a {
  display: block;
  padding: 6px 0;
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
  font-weight: 750;
}

section {
  scroll-margin-top: 86px;
  margin-bottom: 44px;
}

h2 {
  margin: 0 0 18px;
  font-size: 30px;
  line-height: 1.25;
}

h3 {
  margin: 0 0 10px;
  font-size: 18px;
}

p {
  margin: 0 0 16px;
  color: var(--muted);
}

.note,
.article-card,
.topic-card,
.code-explain,
.source-frame-wrap {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 0;
}

.note {
  padding: 16px 18px;
  border-left: 5px solid var(--green);
}

.article-grid,
.topic-grid {
  display: grid;
  gap: 14px;
}

.article-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.topic-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.article-card,
.topic-card {
  display: grid;
  gap: 10px;
  padding: 16px;
  text-decoration: none;
}

.article-card:hover,
.topic-card:hover {
  border-color: rgba(31, 95, 125, 0.46);
  box-shadow: var(--shadow);
}

.status {
  width: max-content;
  padding: 3px 8px;
  color: #163f54;
  background: rgba(85, 183, 232, 0.18);
  border-radius: 0;
  font-size: 12px;
  font-weight: 900;
}

.status.todo {
  color: #5b3b00;
  background: rgba(245, 170, 61, 0.2);
}

.code-explain-list {
  display: grid;
  gap: 16px;
}

.code-explain {
  display: grid;
  gap: 12px;
  padding: 16px;
}

.label {
  display: block;
  margin-bottom: 7px;
  color: var(--green-deep);
  font-size: 13px;
  font-weight: 900;
}

pre {
  margin: 0;
  padding: 13px;
  overflow-x: auto;
  color: #101411;
  background: #ffffff;
  border: 1px solid rgba(16, 20, 17, 0.16);
  border-radius: 0;
  font-size: 13px;
  line-height: 1.45;
}

code {
  padding: 2px 5px;
  color: #101820;
  background: rgba(85, 183, 232, 0.2);
  border-radius: 0;
  font-family: Consolas, "Cascadia Mono", monospace;
  font-size: 0.95em;
}

pre code {
  padding: 0;
  background: transparent;
  border-radius: 0;
}

.detail-note {
  display: grid;
  gap: 8px;
  padding: 12px 14px;
  background: #f8faf6;
  border: 1px solid rgba(16, 20, 17, 0.12);
  border-left: 4px solid var(--green);
  border-radius: 0;
}

.detail-note p {
  margin: 0;
}

.reading-map {
  display: grid;
  gap: 14px;
  margin: 0 0 22px;
}

.reading-map-item {
  padding: 14px 16px;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 0;
}

.reading-map-item strong {
  display: block;
  margin-bottom: 6px;
}

.kernel-figure {
  margin: 20px 0 24px;
  padding: 16px;
  background: #fff;
  border: 1px solid rgba(16, 20, 17, 0.16);
  border-radius: 0;
}

.kernel-figure figcaption {
  margin-bottom: 12px;
  color: #172017;
  font-weight: 900;
}

.figure-caption {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.diagram-canvas {
  display: grid;
  gap: 12px;
  padding: 14px;
  overflow-x: auto;
  background:
    linear-gradient(rgba(16, 20, 17, 0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(16, 20, 17, 0.04) 1px, transparent 1px),
    #fcfdfb;
  background-size: 28px 28px;
  border: 1px solid rgba(16, 20, 17, 0.12);
  border-radius: 0;
}

.diagram-row {
  display: flex;
  align-items: stretch;
  gap: 10px;
  min-width: 720px;
}

.diagram-column {
  display: grid;
  gap: 8px;
  min-width: 160px;
}

.diagram-node {
  min-height: 58px;
  padding: 10px 12px;
  color: #172017;
  background: #fff;
  border: 1px solid rgba(16, 20, 17, 0.22);
  border-radius: 0;
  box-shadow: 0 6px 16px rgba(16, 20, 17, 0.08);
}

.diagram-node strong {
  display: block;
  margin-bottom: 4px;
  font-size: 14px;
}

.diagram-node span {
  display: block;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.45;
}

.diagram-node.accent {
  border-color: rgba(85, 183, 232, 0.82);
  background: #eef8fe;
}

.diagram-node.warn {
  border-color: rgba(245, 170, 61, 0.86);
  background: #fff7e9;
}

.diagram-arrow {
  display: grid;
  place-items: center;
  min-width: 34px;
  color: var(--green-deep);
  font-weight: 900;
}

.state-grid,
.field-table,
.trace-table {
  width: 100%;
  margin: 14px 0 20px;
  border-collapse: collapse;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 0;
  overflow: hidden;
}

.state-grid th,
.state-grid td,
.field-table th,
.field-table td,
.trace-table th,
.trace-table td {
  padding: 10px 12px;
  border-bottom: 1px solid rgba(16, 20, 17, 0.1);
  text-align: left;
  vertical-align: top;
}

.state-grid th,
.field-table th,
.trace-table th {
  color: #17313f;
  background: #e7f3fa;
  font-size: 13px;
}

.state-grid tr:last-child td,
.field-table tr:last-child td,
.trace-table tr:last-child td {
  border-bottom: 0;
}

.field-name,
.state-name {
  color: #18506b;
  font-family: Consolas, "Cascadia Mono", monospace;
  font-weight: 900;
}

.formula-box {
  margin: 14px 0 18px;
  padding: 14px 16px;
  color: #101411;
  background: #fff;
  border: 1px solid rgba(31, 95, 125, 0.28);
  border-left: 5px solid var(--amber);
  border-radius: 0;
  font-family: Consolas, "Cascadia Mono", monospace;
  font-size: 14px;
  line-height: 1.6;
}

.walkthrough {
  display: grid;
  gap: 12px;
  margin: 16px 0 22px;
}

.walkthrough-step {
  padding: 14px 16px;
  background: #fff;
  border: 1px solid rgba(16, 20, 17, 0.14);
  border-radius: 0;
}

.walkthrough-step h3 {
  margin-bottom: 8px;
}

.callout-line {
  margin: 8px 0 0;
  color: var(--muted);
}

.section-brief {
  display: grid;
  gap: 10px;
  margin: 0 0 18px;
  padding: 16px;
  background: #fff;
  border: 1px solid rgba(16, 20, 17, 0.14);
  border-left: 5px solid var(--green);
  border-radius: 0;
}

.section-brief p {
  margin: 0;
}

.analysis-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin: 16px 0 22px;
}

.analysis-card {
  padding: 14px 16px;
  background: #fff;
  border: 1px solid rgba(16, 20, 17, 0.14);
  border-radius: 0;
}

.analysis-card strong {
  display: block;
  margin-bottom: 7px;
}

.analysis-card p {
  margin: 0;
}

.pitfall-list {
  display: grid;
  gap: 12px;
  margin: 0 0 20px;
}

.pitfall-item {
  padding: 14px 16px;
  background: #fff;
  border: 1px solid rgba(245, 170, 61, 0.38);
  border-left: 5px solid var(--amber);
  border-radius: 0;
}

.pitfall-item strong {
  display: block;
  margin-bottom: 6px;
}

.command-note {
  margin: 16px 0 20px;
}

.dense-list {
  display: grid;
  gap: 10px;
  margin: 0 0 18px;
  padding-left: 22px;
  color: var(--muted);
}

.dense-list li {
  padding-left: 2px;
}

.source-frame-head {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  padding: 13px 16px;
  background: #e7f3fa;
  border-bottom: 1px solid var(--line);
  font-weight: 900;
}

.source-frame {
  display: block;
  width: 100%;
  min-height: 640px;
  border: 0;
  background: #fff;
}

.footer {
  color: rgba(247, 251, 244, 0.72);
  background: #0b0f0c;
}

.footer-inner {
  padding: 28px 0;
  font-size: 14px;
}

@media (max-width: 980px) {
  .page-grid,
  .article-grid,
  .topic-grid {
    grid-template-columns: 1fr;
  }

  .toc {
    position: static;
  }

  .diagram-row {
    min-width: 620px;
  }

  .analysis-grid {
    grid-template-columns: 1fr;
  }
}