:root {
  --paper: #f3f6fb;
  --paper-deep: #e8eef8;
  --sheet: #ffffff;
  --ink: #101827;
  --ink-soft: #344054;
  --muted: #667085;
  --line: #d8e0ed;
  --line-strong: #aebed4;
  --azure: #1264d8;
  --azure-deep: #0b3f91;
  --azure-pale: #e7f0fe;
  --cyan: #11a8c4;
  --success: #087a55;
  --warning: #a53b24;
  --serif: Georgia, 'Iowan Old Style', 'Times New Roman', serif;
  --sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  --mono: ui-monospace, 'SFMono-Regular', Menlo, Consolas, monospace;
  --reader-scale: 1;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; }
button, input { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
:focus-visible { outline: 2px solid var(--azure); outline-offset: 3px; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }

.reading-progress {
  position: fixed;
  inset: 0 0 auto;
  z-index: 50;
  height: 3px;
  background: transparent;
}
.reading-progress span {
  display: block;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, var(--azure), var(--cyan));
  transform: scaleX(0);
  transform-origin: left;
}

.reader-shell {
  display: grid;
  grid-template-columns: 280px minmax(0, 780px) 220px;
  gap: 54px;
  max-width: 1450px;
  margin: 0 auto;
  padding: 0 36px;
}

.sidebar,
.page-outline {
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
  scrollbar-width: thin;
}
.sidebar {
  padding: 40px 0 28px;
  border-right: 1px solid var(--line);
}
.brand-block { padding: 0 28px 28px 0; }
.brand {
  display: inline-block;
  color: var(--ink);
  font-family: var(--mono);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-decoration: none;
}
.brand::before {
  content: '';
  display: inline-block;
  width: 9px;
  height: 9px;
  margin-right: 9px;
  background: var(--azure);
  box-shadow: 5px -5px 0 var(--cyan);
}
.brand-subtitle {
  margin: 7px 0 0 27px;
  color: var(--muted);
  font-family: var(--serif);
  font-size: 14px;
  font-style: italic;
}

.search-box {
  position: relative;
  display: flex;
  align-items: center;
  margin: 0 28px 28px 0;
}
.search-box input {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 3px;
  background: var(--sheet);
  color: var(--ink);
  padding: 10px 34px 10px 32px;
  font-size: 13px;
}
.search-mark { position: absolute; left: 11px; color: var(--muted); }
.search-box kbd {
  position: absolute;
  right: 9px;
  border: 1px solid var(--line);
  border-radius: 3px;
  padding: 1px 5px;
  color: var(--muted);
  background: var(--paper);
  font: 10px var(--mono);
}

.nav-group { margin: 0 0 28px; }
.nav-group-title,
.outline-label {
  color: var(--muted);
  font: 600 10px/1.3 var(--mono);
  letter-spacing: 0.14em;
  text-transform: uppercase;
}
.nav-group-title { margin: 0 28px 9px 0; }
.note-link {
  position: relative;
  display: grid;
  grid-template-columns: 38px minmax(0, 1fr);
  gap: 6px;
  padding: 9px 28px 9px 0;
  color: var(--ink-soft);
  text-decoration: none;
  font-size: 13.5px;
  line-height: 1.35;
}
.note-link::after {
  content: '';
  position: absolute;
  inset: 0 0 0 auto;
  width: 3px;
  background: transparent;
}
.note-link:hover { color: var(--azure-deep); }
.note-link.active { color: var(--azure-deep); font-weight: 650; }
.note-link.active::after { background: var(--azure); }
.note-code { color: var(--muted); font: 11px/1.65 var(--mono); }
.nav-empty { color: var(--muted); font-size: 13px; padding-right: 28px; }
.sidebar-actions {
  display: flex;
  gap: 16px;
  margin-right: 28px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
}
.sidebar-actions a {
  color: var(--azure-deep);
  font: 600 10px var(--mono);
  letter-spacing: 0.08em;
  text-decoration: none;
  text-transform: uppercase;
}

.reader-main { min-width: 0; padding: 64px 0 80px; }
.reader-header {
  display: flex;
  justify-content: space-between;
  gap: 28px;
  align-items: flex-start;
  padding-bottom: 30px;
  margin-bottom: 38px;
  border-bottom: 1px solid var(--line-strong);
}
.eyebrow {
  margin-bottom: 10px;
  color: var(--azure);
  font: 600 11px var(--mono);
  letter-spacing: 0.14em;
  text-transform: uppercase;
}
.reader-header h1 {
  margin: 0;
  font: 400 clamp(34px, 5vw, 56px)/1.03 var(--serif);
  letter-spacing: -0.025em;
}
.reader-header p {
  max-width: 62ch;
  margin: 12px 0 0;
  color: var(--ink-soft);
  font: 16px/1.55 var(--serif);
}
.reader-tools { display: flex; flex: 0 0 auto; }
.reader-tools button {
  width: 42px;
  height: 38px;
  border: 1px solid var(--line-strong);
  background: var(--sheet);
  color: var(--ink-soft);
  cursor: pointer;
  font: 600 12px var(--mono);
}
.reader-tools button + button { border-left: 0; }
.reader-tools button:hover { color: var(--azure); background: var(--azure-pale); }

.markdown-body {
  min-height: 55vh;
  font-family: var(--serif);
  font-size: calc(17px * var(--reader-scale));
  line-height: 1.72;
  overflow-wrap: anywhere;
}
.markdown-body > :first-child { margin-top: 0; }
.markdown-body > h1:first-child { display: none; }
.markdown-body h2,
.markdown-body h3,
.markdown-body h4 { scroll-margin-top: 28px; color: var(--ink); }
.markdown-body h2 {
  margin: 64px 0 20px;
  padding-top: 15px;
  border-top: 1px solid var(--line);
  font: 400 calc(30px * var(--reader-scale))/1.18 var(--serif);
  letter-spacing: -0.015em;
}
.markdown-body h3 { margin: 38px 0 13px; font: 600 calc(20px * var(--reader-scale))/1.3 var(--serif); }
.markdown-body h4 { margin: 28px 0 10px; font: 650 calc(16px * var(--reader-scale))/1.4 var(--sans); }
.markdown-body p { margin: 0 0 18px; }
.markdown-body ul,
.markdown-body ol { margin: 0 0 22px; padding-left: 1.35em; }
.markdown-body li { margin: 7px 0; padding-left: 0.2em; }
.markdown-body a { color: var(--azure-deep); text-decoration-color: rgba(18, 100, 216, 0.35); text-underline-offset: 3px; }
.markdown-body strong { color: var(--ink); }
.markdown-body hr { height: 1px; border: 0; background: var(--line); margin: 48px 0; }
.markdown-body blockquote {
  margin: 26px 0;
  padding: 16px 20px;
  border: 1px solid #b9cdeb;
  border-left: 4px solid var(--azure);
  background: var(--azure-pale);
  color: var(--ink-soft);
  font-family: var(--sans);
  font-size: calc(14.5px * var(--reader-scale));
}
.markdown-body blockquote.gotcha { border-color: #e1b7ad; border-left-color: var(--warning); background: #fbefec; }
.markdown-body blockquote p:last-child { margin-bottom: 0; }
.table-wrap { margin: 26px 0 32px; overflow-x: auto; border: 1px solid var(--line); background: var(--sheet); }
.markdown-body table { width: 100%; border-collapse: collapse; font-family: var(--sans); font-size: calc(13.5px * var(--reader-scale)); }
.markdown-body th { background: var(--paper-deep); color: var(--ink); text-align: left; font: 650 11px var(--mono); letter-spacing: 0.05em; text-transform: uppercase; }
.markdown-body th,
.markdown-body td { padding: 11px 13px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); vertical-align: top; }
.markdown-body tr:last-child td { border-bottom: 0; }
.markdown-body th:last-child,
.markdown-body td:last-child { border-right: 0; }
.code-block { position: relative; margin: 26px 0; }
.markdown-body pre {
  margin: 0;
  padding: 20px;
  overflow-x: auto;
  border: 1px solid #26354d;
  border-radius: 3px;
  background: #111a2a;
  color: #d8e6fa;
  font: calc(12.5px * var(--reader-scale))/1.65 var(--mono);
}
.markdown-body :not(pre) > code {
  padding: 0.12em 0.34em;
  border: 1px solid var(--line);
  border-radius: 3px;
  background: var(--sheet);
  color: var(--azure-deep);
  font: 0.88em var(--mono);
}
.copy-code {
  position: absolute;
  top: 8px;
  right: 8px;
  border: 1px solid #42516a;
  border-radius: 3px;
  background: #1d293b;
  color: #c8d7eb;
  cursor: pointer;
  padding: 5px 8px;
  font: 10px var(--mono);
  text-transform: uppercase;
}
.markdown-body details { margin: 20px 0; border: 1px solid var(--line); background: var(--sheet); }
.markdown-body summary { cursor: pointer; padding: 13px 16px; color: var(--azure-deep); font-family: var(--sans); font-weight: 650; }
.markdown-body details > :not(summary) { margin-left: 16px; margin-right: 16px; }

.page-outline { padding: 70px 0 36px; }
.outline-label { margin-bottom: 15px; }
.outline-link {
  display: block;
  padding: 6px 0 6px 12px;
  border-left: 1px solid var(--line);
  color: var(--muted);
  font-size: 12.5px;
  line-height: 1.35;
  text-decoration: none;
}
.outline-link.level-3 { padding-left: 24px; font-size: 12px; }
.outline-link:hover,
.outline-link.active { border-left-color: var(--azure); color: var(--azure-deep); }

.page-turner { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-top: 64px; padding-top: 24px; border-top: 1px solid var(--line); }
.page-link { min-height: 74px; padding: 14px 16px; border: 1px solid var(--line); background: var(--sheet); color: var(--ink-soft); text-decoration: none; }
.page-link.next { text-align: right; }
.page-link:hover { border-color: var(--azure); color: var(--azure-deep); }
.page-link:empty { visibility: hidden; }
.page-link small { display: block; margin-bottom: 5px; color: var(--muted); font: 10px var(--mono); letter-spacing: 0.12em; text-transform: uppercase; }

.loading-state { display: grid; gap: 16px; padding-top: 20px; }
.loading-rule { height: 16px; border-radius: 2px; background: linear-gradient(90deg, var(--paper-deep), var(--sheet), var(--paper-deep)); background-size: 200% 100%; animation: shimmer 1.2s infinite; }
.loading-rule.short { width: 65%; }
.error-state { padding: 22px; border-left: 4px solid var(--warning); background: #fbefec; font-family: var(--sans); }
.mobile-menu,
.mobile-scrim { display: none; }

@keyframes shimmer { to { background-position: -200% 0; } }

@media (max-width: 1120px) {
  .reader-shell { grid-template-columns: 250px minmax(0, 1fr); gap: 42px; }
  .page-outline { display: none; }
}

@media (max-width: 760px) {
  .reader-shell { display: block; padding: 0 20px; }
  .reader-main { padding: 88px 0 56px; }
  .sidebar {
    position: fixed;
    z-index: 40;
    inset: 0 auto 0 0;
    width: min(320px, 86vw);
    height: 100vh;
    padding-left: 22px;
    background: var(--paper);
    transform: translateX(-105%);
    transition: transform 180ms ease;
  }
  body.menu-open .sidebar { transform: translateX(0); }
  body.menu-open { overflow: hidden; }
  .mobile-menu {
    position: fixed;
    z-index: 30;
    top: 16px;
    left: 18px;
    display: flex;
    gap: 10px;
    align-items: center;
    border: 1px solid var(--line-strong);
    border-radius: 3px;
    background: rgba(255, 255, 255, 0.94);
    color: var(--ink);
    padding: 9px 11px;
    font: 600 11px var(--mono);
    letter-spacing: 0.08em;
    text-transform: uppercase;
  }
  .mobile-scrim { position: fixed; z-index: 35; inset: 0; background: rgba(16, 24, 39, 0.35); }
  body.menu-open .mobile-scrim { display: block; }
  .reader-header { display: block; }
  .reader-tools { margin-top: 20px; }
  .markdown-body { font-size: calc(16px * var(--reader-scale)); }
  .page-turner { grid-template-columns: 1fr; }
}

@media print {
  .sidebar, .page-outline, .reader-tools, .mobile-menu, .reading-progress, .page-turner { display: none !important; }
  .reader-shell { display: block; max-width: none; padding: 0; }
  .reader-main { padding: 0; }
  .markdown-body { font-size: 11pt; }
}

@media (prefers-reduced-motion: reduce) {
  * { scroll-behavior: auto !important; transition: none !important; animation: none !important; }
}