/* ═══════════════════════════════════════════════════════
   FIELD MANUAL — Agent Harness Study V4
   DSD: Workshop Field Manual concept
   ═══════════════════════════════════════════════════════ */
:root {
  --paper:      #f3eee3;
  --paper-2:    #e8e1d3;
  --surface:    #ffffff;
  --ink:        #1a1a1a;
  --ink-2:      #3a3a3a;
  --muted:      #7a7a7a;
  --line:       rgba(26,26,26,.14);
  --line-strong:rgba(26,26,26,.28);
  --accent:     #c2410c;
  --accent-2:   #ea580c;
  --accent-deep:#9a3412;
  --alert:      #b91c1c;
  --teal:       #0f766e;
  --deep:       #181818;
  --deep-soft:  #222020;
  --deep-line:  rgba(255,255,255,.10);
  --good:       #15803d;
  --radius-sm:  3px;
  --radius-md:  6px;
  --radius-lg:  10px;
  --shell:      min(1080px, calc(100% - 40px));
  --mono:       "JetBrains Mono","SF Mono","Menlo","Consolas",monospace;
  --sans:       Pretendard,"Apple SD Gothic Neo",-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;
  color-scheme: light;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background:
    linear-gradient(rgba(26,26,26,.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(26,26,26,.035) 1px, transparent 1px),
    var(--paper);
  background-size: 28px 28px, 28px 28px, 100% 100%;
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.7;
  word-break: keep-all;
  overflow-wrap: break-word;
}
a { color: inherit; }
strong, b { font-weight: 700; }
.shell { width: var(--shell); margin-inline: auto; }

/* ── skip ── */
.skip-link { position:absolute;left:16px;top:-80px;z-index:1000;background:var(--ink);color:var(--paper);padding:10px 16px;border-radius:4px;font-size:14px; }
.skip-link:focus { top:16px; }

/* ── header ── */
.site-header {
  position: sticky; top: 0; z-index: 20;
  background: var(--deep);
  border-bottom: 2px solid var(--accent);
}
.nav {
  min-height: 56px;
  display: flex; align-items: center; justify-content: space-between; gap: 24px;
}
.brand {
  display: inline-flex; align-items: center; gap: 10px;
  text-decoration: none; font-weight: 800; color: var(--paper);
  letter-spacing: -.01em;
}
.brand-mark {
  width: 32px; height: 32px;
  display: inline-grid; place-items: center;
  border-radius: var(--radius-sm);
  background: var(--accent);
  color: var(--paper); font-size: 12px; font-weight: 900;
  font-family: var(--mono);
}
.manual-id {
  font-family: var(--mono); font-size: 11px; color: rgba(255,255,255,.45);
  letter-spacing: .08em; text-transform: uppercase;
}
.nav-links { display: flex; align-items: center; gap: 18px; font-size: 13px; }
.nav-links a { text-decoration: none; color: rgba(255,255,255,.7); transition: color .15s; }
.nav-links a:hover { color: var(--accent-2); }

/* ── section base ── */
.section { padding: 80px 0; position: relative; }
.section-deep { background: var(--deep); color: rgba(255,255,255,.88); }
.section-soft { background: var(--paper-2); }

/* harness line — runs through the whole page */
.section::before {
  content: ""; position: absolute; left: 50%; top: 0; bottom: 0;
  width: 1px; background: linear-gradient(var(--line), transparent 120px);
  transform: translateX(-50%);
  pointer-events: none;
}
.section-deep::before { background: linear-gradient(rgba(255,255,255,.06), transparent 120px); }

/* ── chapter header ── */
.chapter-head {
  display: flex; align-items: baseline; gap: 20px;
  margin-bottom: 40px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--line);
}
.chapter-num {
  font-family: var(--mono);
  font-size: 48px; font-weight: 200;
  color: var(--accent); line-height: 1;
  letter-spacing: -.04em;
  flex: 0 0 auto;
}
.chapter-head h2 {
  margin: 0; font-size: clamp(26px, 3.5vw, 38px);
  line-height: 1.12; letter-spacing: -.04em; font-weight: 800;
}
.chapter-head .chapter-label {
  font-family: var(--mono); font-size: 11px; color: var(--muted);
  letter-spacing: .1em; text-transform: uppercase;
  margin-top: 4px; display: block;
}
.section-deep .chapter-head { border-bottom-color: var(--deep-line); }
.section-deep .chapter-num { color: var(--accent-2); }
.section-deep .chapter-head h2 { color: rgba(255,255,255,.95); }
.section-deep .chapter-head .chapter-label { color: rgba(255,255,255,.4); }

/* ── hero / manual cover ── */
.hero { padding: 72px 0 88px; background: var(--deep); color: var(--paper); position: relative; overflow: hidden; }
.hero::before {
  content: ""; position: absolute; inset: 0; opacity: .06;
  background-image:
    linear-gradient(rgba(255,255,255,.4) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,.4) 1px, transparent 1px);
  background-size: 28px 28px;
}
.hero-inner { position: relative; }
.hero-label {
  font-family: var(--mono); font-size: 12px; color: var(--accent-2);
  letter-spacing: .16em; text-transform: uppercase; font-weight: 700;
  margin-bottom: 16px;
}
.hero h1 {
  margin: 0; font-size: clamp(38px, 5.5vw, 64px);
  line-height: 1.05; letter-spacing: -.05em; font-weight: 800;
  max-width: 760px;
}
.hero-lede {
  margin: 24px 0 0; color: rgba(255,255,255,.72);
  font-size: clamp(16px, 1.8vw, 19px); line-height: 1.72;
  max-width: 680px;
}
.hero-actions { margin-top: 32px; display: flex; gap: 10px; flex-wrap: wrap; }
.button {
  min-height: 44px; display: inline-flex; align-items: center; justify-content: center;
  padding: 0 18px; border-radius: var(--radius-sm);
  text-decoration: none; font-weight: 700; font-size: 15px;
  transition: transform .15s, background .15s;
}
.button:hover { transform: translateY(-1px); }
.button.primary { background: var(--accent); color: var(--paper); }
.button.ghost { border: 1px solid rgba(255,255,255,.2); color: rgba(255,255,255,.85); }
.button.small { min-height: 36px; padding: 0 14px; font-size: 13px; }

/* meta grid */
.meta-grid {
  margin-top: 48px;
  display: grid; grid-template-columns: repeat(4, 1fr);
  border: 1px solid rgba(255,255,255,.1); border-radius: var(--radius-md);
  overflow: hidden;
}
.meta-grid > div {
  padding: 20px; border-right: 1px solid rgba(255,255,255,.08);
}
.meta-grid > div:last-child { border-right: 0; }
.meta-grid .meta-label { font-family: var(--mono); font-size: 10px; color: rgba(255,255,255,.4); letter-spacing: .1em; text-transform: uppercase; margin-bottom: 8px; }
.meta-grid .meta-value { font-size: 15px; font-weight: 700; color: rgba(255,255,255,.9); line-height: 1.4; }
.meta-callout {
  margin-top: 20px; padding: 16px 20px;
  border: 1px solid var(--accent); border-radius: var(--radius-sm);
  background: rgba(194,65,12,.12); color: rgba(255,255,255,.85);
  font-size: 15px; line-height: 1.6;
}

/* ── cards (field manual style: border-forward, minimal radius) ── */
.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 24px;
  transition: border-color .15s, transform .15s;
}
.card:hover { border-color: var(--line-strong); transform: translateY(-2px); }

/* ── grids ── */
.grid-2 { display: grid; grid-template-columns: repeat(2,1fr); gap: 16px; }
.grid-3 { display: grid; grid-template-columns: repeat(3,1fr); gap: 16px; }
.grid-4 { display: grid; grid-template-columns: repeat(4,1fr); gap: 16px; }

/* ── problem cards ── */
.problem-card h3, .card h3 { margin: 0 0 10px; font-size: 18px; line-height: 1.25; letter-spacing: -.025em; }
.problem-card p, .card p { margin: 0; color: var(--ink-2); line-height: 1.68; font-size: 15px; }

/* ── deliverable grid ── */
.deliverable-grid { display: grid; grid-template-columns: repeat(4,1fr); gap: 14px; }
.deliverable-grid article {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius-md);
  padding: 22px; transition: border-color .15s, transform .15s;
}
.deliverable-grid article:hover { border-color: var(--accent); transform: translateY(-2px); }
.deliverable-grid .num {
  font-family: var(--mono); font-size: 13px; font-weight: 700;
  color: var(--accent); margin-bottom: 14px; display: block;
}
.deliverable-grid h3 { margin: 0 0 8px; font-size: 16px; letter-spacing: -.02em; }
.deliverable-grid p { margin: 0; font-size: 14px; color: var(--ink-2); line-height: 1.6; }

/* ── flow strip ── */
.flow-strip {
  display: grid; grid-template-columns: repeat(6,1fr);
  border: 1px solid var(--line); border-radius: var(--radius-md); overflow: hidden;
  background: var(--surface);
}
.flow-strip span {
  min-height: 64px; display: flex; align-items: center; gap: 10px;
  padding: 14px 16px; font-weight: 700; font-size: 14px;
  border-right: 1px solid var(--line);
}
.flow-strip span:last-child { border-right: 0; }
.flow-strip span::before {
  content: ""; width: 6px; height: 6px; border-radius: 50%;
  background: var(--accent); flex: 0 0 auto;
}

/* ── timeline (curriculum) ── */
.timeline { display: grid; gap: 16px; }
.week-card {
  position: relative; display: grid; grid-template-columns: 100px 1fr;
  gap: 24px; padding: 24px;
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius-md);
  transition: border-color .15s;
}
.week-card:hover { border-color: var(--line-strong); }
.week-card::before {
  content: ""; position: absolute; left: 72px; top: 90px; bottom: -18px;
  width: 1px; background: linear-gradient(var(--accent), transparent);
}
.week-card:last-child::before { display: none; }
.week-num {
  width: 76px; height: 76px; display: grid; place-items: center;
  border: 2px solid var(--accent); border-radius: var(--radius-sm);
  font-family: var(--mono); font-weight: 800; font-size: 14px; color: var(--accent-deep);
  background: var(--paper);
}
.week-card h3 { margin: 0 0 6px; font-size: 20px; letter-spacing: -.03em; }
.week-card h4 { margin: 20px 0 8px; font-size: 15px; letter-spacing: -.02em; color: var(--ink); }
.week-sub { margin: 0 0 12px; font-weight: 700; color: var(--teal); font-size: 15px; }
.week-card p { margin: 0 0 14px; color: var(--ink-2); font-size: 15px; line-height: 1.7; }
.assignment-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin: 12px 0 14px; }
.assignment-card { padding: 14px; border: 1px solid var(--line); border-radius: var(--radius-sm); background: var(--paper); }
.assignment-card strong { display: block; margin-bottom: 6px; color: var(--accent-deep); font-size: 13px; }
.assignment-card span { display: block; color: var(--ink-2); font-size: 14px; line-height: 1.55; }
.week-card ul { margin: 12px 0 0; padding-left: 1.2rem; }
.week-card li { font-size: 14px; color: var(--ink-2); line-height: 1.6; }
.week-card li span { display: block; margin-top: 3px; color: var(--muted); }
li + li { margin-top: 6px; }

/* ── tools ── */
.tools-grid { display: grid; grid-template-columns: 1fr repeat(3,.75fr); gap: 16px; align-items: stretch; }
.tools h2 { margin: 0; font-size: clamp(26px,3.5vw,38px); line-height: 1.1; letter-spacing: -.04em; }
.tool-card { padding: 24px; border: 1px solid var(--deep-line); border-radius: var(--radius-md); background: rgba(255,255,255,.05); }
.tool-card p { color: rgba(255,255,255,.72); font-size: 15px; }
.tool-card.accent { background: rgba(194,65,12,.12); border-color: rgba(194,65,12,.3); }

/* ── leader ── */
.leader-grid { display: grid; grid-template-columns: 1fr; gap: 16px; }
.leader-bio, .promise-card { padding: 28px; }
.leader-bio { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius-md); }
.leader-bio ul { margin: 0; padding-left: 1.2rem; }
.leader-bio li { color: var(--ink-2); font-size: 15px; }
.promise-card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius-md); }
.promise-card h3 { margin: 0 0 14px; font-size: 20px; letter-spacing: -.03em; }
.promise-list { margin: 0; padding-left: 1.3rem; }
.promise-list li { padding: 12px 0; border-top: 1px solid var(--line); }
.promise-list li:first-child { border-top: 0; padding-top: 0; }
.promise-list strong { display: block; margin-bottom: 4px; color: var(--ink); }
.promise-list span { display: block; color: var(--ink-2); font-size: 15px; line-height: 1.6; }

/* ── pricing ── */
.pricing-grid { display: grid; grid-template-columns: repeat(4,1fr); gap: 14px; }

/* ── track record ── */
.track-content { padding: 32px; }
.track-content > p { color: var(--ink-2); line-height: 1.78; margin: 16px 0 0; }
.track-stats { display: grid; grid-template-columns: repeat(3,1fr); gap: 14px; margin: 24px 0; }
.stat-item { text-align: center; padding: 20px; border: 1px solid var(--line); border-radius: var(--radius-sm); background: var(--surface); }
.stat-item strong { display: block; font-size: 26px; color: var(--accent-deep); letter-spacing: -.03em; margin-bottom: 4px; }
.stat-item span { color: var(--muted); font-size: 13px; }
.track-lede { margin-top: 0 !important; font-size: 16px; }
.ranking-hero { display: grid; grid-template-columns: repeat(5, minmax(0,1fr)); gap: 14px; margin: 24px 0 18px; }
.ranking-card { border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--paper); padding: 22px 16px; min-height: 150px; display: flex; flex-direction: column; justify-content: space-between; }
.ranking-card.primary { border-color: var(--accent); background: rgba(194,65,12,.08); }
.ranking-card span { font-size: 13px; color: var(--muted); font-weight: 700; }
.ranking-card strong { display: block; font-size: clamp(32px, 4vw, 48px); line-height: 1; color: var(--accent-deep); letter-spacing: -.05em; margin: 16px 0 10px; }
.ranking-card em { font-style: normal; font-size: 13px; color: var(--ink-2); }
.track-stats.compact { margin-top: 18px; }

/* ── final share ── */
.final-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.final-col { padding: 28px; }
.final-col h3 { margin: 0 0 14px; font-size: 18px; }
.final-col ul { margin: 0; }
.final-col li { font-size: 15px; color: var(--ink-2); }

/* ── check list (dark) ── */
.fit-grid { display: grid; grid-template-columns: repeat(2,1fr); gap: 18px; align-items: stretch; }
.fit-grid h3 { margin: 0 0 14px; color: rgba(255,255,255,.92); font-size: 18px; letter-spacing: -.02em; }
.fit-column { display: flex; flex-direction: column; min-height: 100%; }
.fit-column .check-list { flex: 1; }
.check-list { display: grid; gap: 10px; grid-auto-rows: 1fr; }
.check-item {
  display: flex; align-items: flex-start; gap: 14px; height: 100%;
  padding: 18px 20px; border: 1px solid var(--deep-line); border-radius: var(--radius-sm);
  background: rgba(255,255,255,.04);
}
.check-item .x {
  flex: 0 0 auto; width: 28px; height: 28px;
  display: grid; place-items: center; border-radius: var(--radius-sm);
  background: rgba(185,28,28,.18); color: #f87171; font-weight: 900; font-size: 14px;
  font-family: var(--mono);
}
.check-item .ok {
  flex: 0 0 auto; width: 28px; height: 28px;
  display: grid; place-items: center; border-radius: var(--radius-sm);
  background: rgba(21,128,61,.20); color: #86efac; font-weight: 900; font-size: 14px;
  font-family: var(--mono);
}
.check-item p { margin: 0; color: rgba(255,255,255,.76); font-size: 15px; line-height: 1.6; }

/* ── motivation ── */
.motivation-text { padding: 32px; }
.motivation-text p { color: var(--ink-2); line-height: 1.82; margin: 16px 0 0; font-size: 15px; }
.motivation-text p:first-child { margin-top: 0; }

/* ── video cards ── */
.video-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; margin-bottom: 20px; }
.video-card { padding: 26px; }
.video-badge { display: inline-flex; align-items: center; padding: 4px 12px; border: 1px solid var(--accent); border-radius: var(--radius-sm); color: var(--accent-deep); font-family: var(--mono); font-weight: 700; font-size: 11px; letter-spacing: .06em; margin-bottom: 14px; }
.video-card h3 { margin: 0 0 10px; font-size: 18px; line-height: 1.25; }
.video-card p { margin: 0 0 16px; font-size: 15px; }

/* ── prereq ── */
.prereq-grid { margin-top: 16px; align-items: stretch; }
.prereq-card { padding: 28px; }
.prereq-card h3 { margin: 0 0 14px; font-size: 18px; }
.prereq-card ul { margin: 0; }
.prereq-card li { font-size: 15px; color: var(--ink-2); }
.reference-card a { color: var(--accent-deep); font-weight: 700; text-decoration-thickness: 1px; text-underline-offset: 3px; }

/* ── FAQ ── */
.faq-list { display: grid; gap: 10px; }
.faq-item {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius-sm);
  overflow: hidden;
}
.faq-item summary {
  cursor: pointer; list-style: none; position: relative;
  padding: 18px 56px 18px 20px; font-size: 16px; font-weight: 700;
  line-height: 1.4; letter-spacing: -.02em;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+"; position: absolute; right: 20px; top: 50%; transform: translateY(-50%);
  width: 28px; height: 28px; display: grid; place-items: center;
  border: 1px solid var(--line); border-radius: var(--radius-sm);
  color: var(--accent); font-weight: 900; font-family: var(--mono); font-size: 16px;
}
.faq-item[open] summary::after { content: "–"; }
.faq-answer { padding: 0 20px 20px; color: var(--ink-2); }
.faq-answer p { margin: 10px 0 0; line-height: 1.75; font-size: 15px; }

/* ── footer ── */
.footer { padding: 28px 0; border-top: 2px solid var(--accent); background: var(--deep); }
.footer-inner { display: flex; justify-content: space-between; gap: 16px; color: rgba(255,255,255,.5); font-family: var(--mono); font-size: 12px; letter-spacing: .05em; }
.footer a { color: var(--accent-2); font-weight: 700; text-decoration: none; }

@media (max-width: 1180px) and (min-width: 961px) {
  .ranking-hero { grid-template-columns: repeat(3, minmax(0,1fr)); }
}

/* ── responsive ── */
@media (max-width: 960px) {
  .nav-links { display: none; }
  .meta-grid, .grid-2, .grid-3, .grid-4, .deliverable-grid, .tools-grid,
  .video-grid, .pricing-grid, .final-grid, .track-stats, .ranking-hero, .fit-grid, .flow-strip { grid-template-columns: 1fr; }
  .flow-strip span { border-bottom: 1px solid var(--line); }
  .week-card { grid-template-columns: 1fr; }
  .week-card::before { display: none; }
  .assignment-grid { grid-template-columns: 1fr; }
  .manual-id { display: none; }
}
@media (max-width: 640px) {
  :root { --shell: min(100% - 24px, 1080px); }
  .section { padding: 56px 0; }
  .hero { padding: 48px 0 64px; }
  .chapter-num { font-size: 36px; }
  .footer-inner { flex-direction: column; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition: none !important; }
}