:root {
  --paper: #f4f7fb;
  --paper-strong: #e8eef7;
  --ink: #17263a;
  --muted: #607089;
  --line: #b9c7d9;
  --blue: #285d91;
  --blue-dark: #173e67;
  --signal: #c66a42;
  --white: #ffffff;
  --shadow: 0 16px 40px rgba(28, 55, 85, .09);
  --max: 1180px;
}
* { box-sizing: border-box; }
html { color-scheme: light; scroll-behavior: smooth; }
body { margin: 0; background: var(--paper); color: var(--ink); font-family: ui-serif, Georgia, "Songti SC", "Noto Serif CJK SC", serif; line-height: 1.72; overflow-wrap: anywhere; }
body::before { content: ""; position: fixed; inset: 0; pointer-events: none; opacity: .35; background-image: linear-gradient(rgba(40,93,145,.04) 1px, transparent 1px), linear-gradient(90deg, rgba(40,93,145,.04) 1px, transparent 1px); background-size: 24px 24px; z-index: -1; }
a { color: inherit; text-decoration-thickness: .08em; text-underline-offset: .18em; }
a:hover { color: var(--blue); }
button, input { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
code { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: .9em; background: var(--paper-strong); padding: .1em .35em; border-radius: 4px; }
.skip-link { position: fixed; top: .5rem; left: .5rem; z-index: 100; transform: translateY(-150%); padding: .6rem .9rem; color: white; background: var(--blue-dark); }
.skip-link:focus { transform: none; }
.site-header { width: min(calc(100% - 40px), var(--max)); margin: 18px auto 0; border: 1px solid var(--line); background: rgba(244,247,251,.94); box-shadow: var(--shadow); }
.topline { display: flex; justify-content: space-between; align-items: center; gap: 1rem; padding: 18px 22px; border-bottom: 1px solid var(--line); }
.wordmark { font-weight: 800; letter-spacing: .08em; text-decoration: none; }
.topline span { color: var(--muted); font: 700 .72rem/1.4 ui-monospace, SFMono-Regular, Menlo, monospace; text-transform: uppercase; }
.nav-panel { display: flex; gap: 0; overflow-x: auto; scrollbar-width: thin; }
.nav-panel a { flex: 0 0 auto; padding: 11px 16px; border-right: 1px solid var(--line); font: 700 .84rem/1.3 ui-sans-serif, system-ui, sans-serif; text-decoration: none; }
.nav-panel a:hover, .nav-panel a:focus-visible { background: var(--paper-strong); }
.nav-toggle { display: none; width: 100%; align-items: center; justify-content: space-between; border: 0; border-bottom: 1px solid var(--line); padding: 12px 16px; color: var(--ink); background: var(--white); }
main { width: min(calc(100% - 40px), var(--max)); margin: 0 auto; }
.breadcrumb { display: flex; gap: .65rem; align-items: center; padding: 20px 4px 0; color: var(--muted); font: 600 .8rem/1.4 ui-sans-serif, system-ui, sans-serif; }
.hero { min-height: 590px; display: grid; grid-template-columns: minmax(0, 1.35fr) minmax(280px, .65fr); align-items: center; gap: clamp(2rem, 7vw, 7rem); padding: clamp(50px, 8vw, 100px) clamp(0px, 3vw, 40px); border-bottom: 1px solid var(--line); }
.eyebrow, .section-no { margin: 0 0 1rem; color: var(--blue); font: 800 .74rem/1.4 ui-monospace, SFMono-Regular, Menlo, monospace; letter-spacing: .12em; text-transform: uppercase; }
h1, h2, h3 { line-height: 1.2; letter-spacing: -.025em; }
h1 { margin: 0; font-size: clamp(2.7rem, 7vw, 6.8rem); max-width: 9em; }
.page-intro h1 { font-size: clamp(2.2rem, 5vw, 4.8rem); max-width: 15em; }
h2 { margin: 0 0 1.1rem; font-size: clamp(1.65rem, 3vw, 2.65rem); }
h3 { margin: 0; font-size: 1.15rem; }
p { margin: 0 0 1rem; }
.lead { max-width: 760px; margin: 1.5rem 0 0; color: #354b65; font-size: clamp(1.04rem, 1.7vw, 1.32rem); }
.hero-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 2rem; }
.button { display: inline-flex; min-height: 44px; align-items: center; justify-content: center; padding: 10px 16px; border: 1px solid var(--blue); color: var(--blue-dark); font: 800 .9rem/1.2 ui-sans-serif, system-ui, sans-serif; text-decoration: none; background: transparent; }
.button.primary { background: var(--blue-dark); color: white; }
.status-line { max-width: 680px; margin-top: 1.4rem; padding-left: 14px; border-left: 3px solid var(--signal); color: var(--muted); font-size: .9rem; }
.compass { position: relative; width: min(100%, 360px); aspect-ratio: 1; margin: auto; border: 1px solid var(--line); border-radius: 50%; background: radial-gradient(circle, var(--white) 0 13%, transparent 13.5%), conic-gradient(from 45deg, rgba(40,93,145,.16), transparent 25%, rgba(40,93,145,.08) 50%, transparent 75%, rgba(40,93,145,.16)); box-shadow: inset 0 0 0 22px var(--paper), inset 0 0 0 23px var(--line); }
.compass::before, .compass::after { content: ""; position: absolute; background: var(--line); }
.compass::before { left: 50%; top: 8%; bottom: 8%; width: 1px; }
.compass::after { top: 50%; left: 8%; right: 8%; height: 1px; }
.compass span, .compass b { position: absolute; z-index: 1; font: 800 .82rem/1 ui-sans-serif, system-ui, sans-serif; letter-spacing: .1em; }
.compass .north { top: 4%; left: 50%; transform: translateX(-50%); }
.compass .south { bottom: 4%; left: 50%; transform: translateX(-50%); }
.compass .east { right: 3%; top: 50%; transform: translateY(-50%); }
.compass .west { left: 3%; top: 50%; transform: translateY(-50%); }
.compass b { top: 50%; left: 50%; transform: translate(-50%, -50%); color: var(--blue); }
.orientation, .depth-section, .method-strip { display: grid; grid-template-columns: minmax(0, .75fr) minmax(0, 1.25fr); gap: clamp(2rem, 6vw, 6rem); padding: clamp(60px, 8vw, 100px) 0; border-bottom: 1px solid var(--line); }
.prose, .two-col { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: clamp(1.2rem, 3vw, 3rem); }
.prose p:first-child::first-letter { float: left; margin: .05em .12em 0 0; color: var(--blue); font-size: 3.4em; line-height: .8; }
.index-section, .faq-section { padding: clamp(60px, 8vw, 100px) 0; border-bottom: 1px solid var(--line); }
.section-heading { display: flex; justify-content: space-between; align-items: end; gap: 2rem; margin-bottom: 2rem; }
.filter-tabs { display: flex; flex-wrap: wrap; gap: 6px; }
.filter-tabs button { min-height: 40px; padding: 7px 12px; border: 1px solid var(--line); background: transparent; color: var(--ink); cursor: pointer; }
.filter-tabs button[aria-pressed="true"] { background: var(--blue-dark); color: white; border-color: var(--blue-dark); }
.editorial-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 14px; }
.editorial-grid.compact { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.note-card { position: relative; min-width: 0; min-height: 260px; display: flex; flex-direction: column; padding: 22px; border: 1px solid var(--line); background: rgba(255,255,255,.54); }
.note-card::before { content: ""; position: absolute; inset: 7px; pointer-events: none; border-top: 1px solid rgba(40,93,145,.18); border-left: 1px solid rgba(40,93,145,.18); }
.note-card[hidden] { display: none; }
.note-card h3 { margin: 1rem 0; }
.note-card p { color: var(--muted); }
.note-card .text-link { margin-top: auto; font-weight: 800; }
.card-index { align-self: end; color: var(--blue); font: 800 .75rem/1 ui-monospace, monospace; }
.evidence { margin-top: auto; padding-top: 1rem; border-top: 1px dashed var(--line); font-size: .86rem; }
.brief-list { border-top: 1px solid var(--line); }
.brief-row { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, .8fr); gap: 2rem; padding: 24px 0; border-bottom: 1px solid var(--line); }
.brief-row span { color: var(--blue); font: 700 .72rem/1.4 ui-monospace, monospace; }
.brief-row p { color: var(--muted); }
.method-strip ol { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1px; margin: 0; padding: 1px; list-style: none; background: var(--line); }
.method-strip li { display: grid; gap: .5rem; padding: 20px; background: var(--paper); }
.method-strip span { color: var(--muted); }
.faq-section details { border-top: 1px solid var(--line); padding: 20px 0; }
.faq-section details:last-child { border-bottom: 1px solid var(--line); }
.faq-section summary { cursor: pointer; font-weight: 800; }
.faq-section details p { max-width: 760px; margin: 1rem 0 0; color: var(--muted); }
.page-shell { padding: clamp(45px, 7vw, 90px) 0; }
.page-intro { max-width: 940px; padding-bottom: clamp(45px, 7vw, 80px); border-bottom: 1px solid var(--line); }
.page-shell > section, .page-shell > aside { padding: clamp(40px, 6vw, 70px) 0; border-bottom: 1px solid var(--line); }
.page-shell > section > p { max-width: 820px; }
.meta-line { display: flex; flex-wrap: wrap; gap: 8px 18px; margin-top: 1.5rem; color: var(--muted); font: 700 .78rem/1.5 ui-sans-serif, system-ui, sans-serif; }
.check-steps { max-width: 900px; margin: 0; padding: 0; list-style: none; counter-reset: steps; }
.check-steps li { display: grid; grid-template-columns: minmax(140px, .38fr) minmax(0, 1fr); gap: 1rem; padding: 18px 0; border-top: 1px solid var(--line); }
.check-steps li:last-child { border-bottom: 1px solid var(--line); }
.check-steps span { color: var(--muted); }
.boundary-note { padding-left: clamp(18px, 4vw, 44px) !important; border-left: 4px solid var(--signal); background: linear-gradient(90deg, rgba(198,106,66,.08), transparent 70%); }
.boundary-note p { max-width: 800px; }
.tag-row { display: flex; flex-wrap: wrap; gap: 8px; }
.tag-row a, .footer-links a { padding: 5px 9px; border: 1px solid var(--line); text-decoration: none; font: 700 .78rem/1.4 ui-sans-serif, system-ui, sans-serif; }
.related-list, .authored-list { max-width: 880px; margin: 1.5rem 0 0; padding: 0; list-style: none; border-top: 1px solid var(--line); }
.related-list li, .authored-list li { display: grid; gap: .4rem; padding: 14px 0; border-bottom: 1px solid var(--line); }
.authored-list span { color: var(--muted); }
.tool-checklist { max-width: 900px; margin: 0; padding: 0; list-style: none; }
.tool-checklist label { display: block; cursor: pointer; }
.tool-checklist input { position: absolute; opacity: 0; }
.tool-checklist span { display: grid; grid-template-columns: 52px minmax(0, 1fr); gap: 1rem; align-items: center; padding: 18px; border: 1px solid var(--line); margin-top: -1px; background: rgba(255,255,255,.45); }
.tool-checklist input:focus-visible + span { outline: 3px solid rgba(40,93,145,.28); outline-offset: 2px; }
.tool-checklist input:checked + span { background: #dce9f5; text-decoration: line-through; color: var(--muted); }
.tool-checklist b { color: var(--blue); font-family: ui-monospace, monospace; }
.sample-note { max-width: 820px; padding: 22px; border: 1px dashed var(--blue); background: var(--white); }
.not-found { min-height: 620px; }
.site-footer { width: min(calc(100% - 40px), var(--max)); margin: 0 auto 24px; display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 1px; border: 1px solid var(--line); background: var(--line); }
.site-footer section { min-width: 0; padding: 20px; background: var(--paper-strong); }
.site-footer h2 { font-size: 1rem; }
.footer-links { display: flex; flex-wrap: wrap; gap: 6px; }
.fine-print { grid-column: 1 / -1; margin: 0; padding: 18px 20px; color: var(--muted); background: var(--paper); font-size: .82rem; }
@media (max-width: 900px) {
  .hero { min-height: auto; grid-template-columns: minmax(0, 1fr); }
  .compass { width: min(70vw, 330px); }
  .orientation, .depth-section, .method-strip { grid-template-columns: minmax(0, 1fr); gap: 1rem; }
  .editorial-grid, .editorial-grid.compact { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .site-footer { grid-template-columns: minmax(0, 1fr); }
  .fine-print { grid-column: auto; }
}
@media (max-width: 620px) {
  .site-header, main, .site-footer { width: min(calc(100% - 24px), var(--max)); }
  .site-header { margin-top: 10px; }
  .topline { padding: 13px 14px; }
  .topline span { display: none; }
  .nav-toggle { display: flex; }
  .js-ready .nav-panel { display: none; }
  .js-ready .nav-panel.is-open { display: grid; }
  .nav-panel { display: grid; overflow: visible; }
  .nav-panel a { border-right: 0; border-bottom: 1px solid var(--line); }
  .hero { gap: 2.2rem; padding: 48px 0 58px; }
  h1 { font-size: clamp(2.35rem, 13vw, 4rem); }
  .page-intro h1 { font-size: clamp(2rem, 10vw, 3.3rem); }
  .compass { width: min(86vw, 300px); }
  .hero-actions { display: grid; }
  .button { width: 100%; }
  .prose, .two-col, .editorial-grid, .editorial-grid.compact, .method-strip ol { grid-template-columns: minmax(0, 1fr); }
  .section-heading { display: grid; align-items: start; }
  .filter-tabs { width: 100%; }
  .filter-tabs button { flex: 1 1 auto; }
  .note-card { min-height: 220px; }
  .brief-row, .check-steps li { grid-template-columns: minmax(0, 1fr); gap: .6rem; }
  .page-shell { padding-top: 38px; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }