/* ==========================================================================
   Level 2 · 실무 백엔드 — 교재 안내서
   Level 1 안내서와 같은 토큰 체계(색·글꼴·간격). 강조색만 Level 2 정체성(청록)으로.
   토큰 → 기본 → 레이아웃 → 컴포넌트 → 섹션별 → 반응형 순서
   ========================================================================== */

:root {
  --bg: #f4f6f5;
  --bg-elev: #ffffff;
  --bg-sunk: #e8edec;
  --ink: #111a1b;
  --ink-2: #34403f;
  --muted: #5e6b6c;
  --line: #dce3e1;
  --line-strong: #c3cecb;

  --accent: #0f766e;          /* Level 2 · 운영 */
  --accent-ink: #ffffff;
  --accent-soft: #d6efea;
  --break: #c0262d;           /* 깨지는 지점 · 사고 */
  --break-soft: #fbe3e2;
  --ok: #157a3c;
  --ok-soft: #dcf1e3;
  --warn: #9a6700;
  --warn-soft: #fbefd0;
  --l1: #c2410c;              /* Level 1 표시(칩) */
  --l1-soft: #fbe8dc;

  /* 계층 색 — 실패 지도·구성도 */
  --c-web: #6d28d9;
  --c-dns: #0e7490;
  --c-edge: #0f766e;
  --c-app: #1d4ed8;
  --c-db: #b45309;
  --c-mq: #be185d;
  --c-ws: #4d7c0f;

  --code-bg: #151b1c;
  --code-ink: #e6ecea;
  --code-dim: #8b9a98;

  --shadow-sm: 0 1px 2px rgba(15, 25, 25, .05);
  --shadow: 0 1px 2px rgba(15, 25, 25, .04), 0 12px 32px -16px rgba(15, 25, 25, .18);
  --radius: 14px;
  --radius-sm: 9px;
  --wrap: 1120px;
  --gutter: 24px;
  --nav-h: 60px;

  --font: "Pretendard Variable", Pretendard, -apple-system, BlinkMacSystemFont, "Apple SD Gothic Neo",
    "Malgun Gothic", "Noto Sans KR", system-ui, sans-serif;
  --mono: "JetBrains Mono", "Pretendard Variable", Pretendard, ui-monospace, SFMono-Regular, Menlo, Consolas, "D2Coding", monospace;

  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0c1213;
    --bg-elev: #131b1c;
    --bg-sunk: #091011;
    --ink: #e7eeed;
    --ink-2: #c1cdcb;
    --muted: #8d9e9c;
    --line: #223032;
    --line-strong: #324441;
    --accent: #2dd4bf;
    --accent-ink: #032420;
    --accent-soft: #0e2d29;
    --break: #ff6b6b;
    --break-soft: #3a1516;
    --ok: #4ade80;
    --ok-soft: #11291a;
    --warn: #f2c14e;
    --warn-soft: #2e2510;
    --l1: #ff7a45;
    --l1-soft: #34190d;
    --c-web: #a78bfa;
    --c-dns: #22d3ee;
    --c-edge: #2dd4bf;
    --c-app: #7ea4ff;
    --c-db: #fbbf24;
    --c-mq: #f472b6;
    --c-ws: #a3e635;
    --code-bg: #091011;
    --shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 12px 32px -16px rgba(0, 0, 0, .6);
    color-scheme: dark;
  }
}

:root[data-theme="dark"] {
  --bg: #0c1213;
  --bg-elev: #131b1c;
  --bg-sunk: #091011;
  --ink: #e7eeed;
  --ink-2: #c1cdcb;
  --muted: #8d9e9c;
  --line: #223032;
  --line-strong: #324441;
  --accent: #2dd4bf;
  --accent-ink: #032420;
  --accent-soft: #0e2d29;
  --break: #ff6b6b;
  --break-soft: #3a1516;
  --ok: #4ade80;
  --ok-soft: #11291a;
  --warn: #f2c14e;
  --warn-soft: #2e2510;
  --l1: #ff7a45;
  --l1-soft: #34190d;
  --c-web: #a78bfa;
  --c-dns: #22d3ee;
  --c-edge: #2dd4bf;
  --c-app: #7ea4ff;
  --c-db: #fbbf24;
  --c-mq: #f472b6;
  --c-ws: #a3e635;
  --code-bg: #091011;
  --shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 12px 32px -16px rgba(0, 0, 0, .6);
  color-scheme: dark;
}

/* ---------- 기본 ---------- */
*, *::before, *::after { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-h) + 16px);
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font);
  font-size: 16.5px;
  line-height: 1.7;
  word-break: keep-all;
  overflow-wrap: break-word;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4 { line-height: 1.3; margin: 0; letter-spacing: -0.02em; }
p { margin: 0 0 1em; }
ul, ol { margin: 0; padding: 0; }
a { color: inherit; }
strong { font-weight: 700; }
code, kbd, pre { font-family: var(--mono); font-variant-ligatures: none; }
:not(pre) > code {
  font-size: .86em;
  padding: .12em .4em;
  border-radius: 6px;
  background: var(--bg-sunk);
  border: 1px solid var(--line);
  overflow-wrap: anywhere;
}
::selection { background: var(--accent); color: var(--accent-ink); }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 6px;
}

.wrap {
  width: 100%;
  max-width: calc(var(--wrap) + var(--gutter) * 2);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

.skip {
  position: absolute;
  left: 12px;
  top: -48px;
  padding: 8px 14px;
  background: var(--ink);
  color: var(--bg);
  border-radius: 8px;
  z-index: 100;
  text-decoration: none;
}
.skip:focus { top: 12px; }

.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;
}

/* ---------- 상단 내비게이션 ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  height: var(--nav-h);
  background: color-mix(in srgb, var(--bg) 86%, transparent);
  backdrop-filter: saturate(160%) blur(12px);
  -webkit-backdrop-filter: saturate(160%) blur(12px);
  border-bottom: 1px solid var(--line);
}
.nav .wrap {
  height: 100%;
  display: flex;
  align-items: center;
  gap: 20px;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  letter-spacing: -0.02em;
  text-decoration: none;
  white-space: nowrap;
  font-size: 15px;
}
.brand-mark { width: 26px; height: 26px; flex: none; }
.brand .lv {
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 700;
  padding: 1px 6px;
  border-radius: 5px;
  color: var(--accent-ink);
  background: var(--accent);
  letter-spacing: .04em;
}
.nav-links {
  display: flex;
  gap: 2px;
  margin-left: auto;
  list-style: none;
}
.nav-links a {
  display: block;
  padding: 6px 10px;
  border-radius: 8px;
  font-size: 14.5px;
  font-weight: 500;
  color: var(--muted);
  text-decoration: none;
  white-space: nowrap;
  transition: color .15s, background .15s;
}
.nav-links a:hover { color: var(--ink); background: var(--bg-sunk); }
.nav-links a.active { color: var(--ink); background: var(--bg-sunk); font-weight: 650; }
.nav-links a.ext { color: var(--accent); font-weight: 650; }
.nav-actions { display: flex; align-items: center; gap: 6px; }
.icon-btn {
  display: inline-grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border-radius: 9px;
  border: 1px solid var(--line);
  background: var(--bg-elev);
  color: var(--ink-2);
  cursor: pointer;
  text-decoration: none;
  transition: border-color .15s, color .15s;
}
.icon-btn:hover { border-color: var(--line-strong); color: var(--ink); }
.icon-btn svg { width: 18px; height: 18px; }
.menu-btn { display: none; }
.theme-btn .i-sun { display: none; }
:root[data-theme="dark"] .theme-btn .i-sun { display: block; }
:root[data-theme="dark"] .theme-btn .i-moon { display: none; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .theme-btn .i-sun { display: block; }
  :root:not([data-theme="light"]) .theme-btn .i-moon { display: none; }
}

/* ---------- 버튼·배지·칩 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 18px;
  border-radius: 10px;
  border: 1px solid var(--line-strong);
  background: var(--bg-elev);
  color: var(--ink);
  font-weight: 650;
  font-size: 15px;
  text-decoration: none;
  cursor: pointer;
  font-family: inherit;
  transition: transform .15s, border-color .15s, background .15s;
}
.btn:hover { border-color: var(--ink-2); }
.btn:active { transform: translateY(1px); }
.btn.primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.btn.primary:hover { background: color-mix(in srgb, var(--accent) 86%, var(--ink)); }
.btn.small { padding: 7px 12px; font-size: 13.5px; border-radius: 8px; }

.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 2px 10px;
  border-radius: 999px;
  font-size: 12.5px;
  font-weight: 650;
  white-space: nowrap;
  line-height: 1.6;
}
.badge::before { content: ""; width: 7px; height: 7px; border-radius: 50%; background: currentColor; }
.badge.design { color: var(--muted); background: var(--bg-sunk); }
.badge.writing { color: var(--warn); background: var(--warn-soft); }
.badge.published { color: var(--ok); background: var(--ok-soft); }
.badge.plain::before { display: none; }

.chip {
  display: inline-flex;
  align-items: center;
  padding: 1px 8px;
  border-radius: 6px;
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 650;
  line-height: 1.75;
  white-space: nowrap;
  text-decoration: none;
  color: var(--l1);
  background: var(--l1-soft);
  border: 1px solid transparent;
  transition: border-color .15s;
}
a.chip:hover { border-color: var(--l1); }
.chip.new { color: var(--accent); background: var(--accent-soft); font-family: var(--font); }
.chip.ora { color: var(--c-db); background: color-mix(in srgb, var(--c-db) 13%, transparent); font-family: var(--font); }
.chip.ora, .chip.new { white-space: normal; max-width: 100%; }
.chips { display: flex; flex-wrap: wrap; gap: 5px; }

.mark {
  display: inline-grid;
  place-items: center;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  font-family: var(--mono);
  font-size: 11.5px;
  font-weight: 700;
  color: #fff;
  background: var(--break);
  text-decoration: none;
  flex: none;
  box-shadow: 0 0 0 3px var(--bg-elev);
  transition: transform .15s;
}
:root[data-theme="dark"] .mark { color: #200606; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .mark { color: #200606; } }
a.mark:hover { transform: scale(1.12); }

/* ---------- 섹션 공통 ---------- */
.section { padding: 96px 0; border-bottom: 1px solid var(--line); }
.section.sunk { background: var(--bg-sunk); }
.sec-head { max-width: 760px; margin-bottom: 40px; }
.sec-kicker {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--mono);
  font-size: 12.5px;
  font-weight: 650;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 12px;
}
.sec-kicker::after { content: ""; width: 36px; height: 1px; background: currentColor; opacity: .6; }
.sec-head h2 { font-size: clamp(1.75rem, 3.4vw, 2.35rem); font-weight: 820; letter-spacing: -0.03em; margin-bottom: 14px; }
.sec-head p { color: var(--ink-2); font-size: 1.05rem; margin: 0; }
.sub-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  margin: 56px 0 18px;
}
.sub-head h3 { font-size: 1.3rem; font-weight: 780; }
.sub-head p { margin: 0; color: var(--muted); font-size: 14.5px; }

.grid { display: grid; gap: 16px; }
.grid.c2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid.c3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid.c4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

.card {
  position: relative;
  padding: 22px 22px 20px;
  border-radius: var(--radius);
  background: var(--bg-elev);
  border: 1px solid var(--line);
  box-shadow: var(--shadow-sm);
}
.card h3, .card h4 { font-size: 1.06rem; font-weight: 750; margin-bottom: 8px; }
.card p { color: var(--ink-2); font-size: 15px; margin: 0; }
.card p + p { margin-top: 10px; }
.card .num {
  display: block;
  font-family: var(--mono);
  font-size: 12.5px;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 10px;
}

.list { list-style: none; display: grid; gap: 7px; font-size: 15px; color: var(--ink-2); }
.list li { position: relative; padding-left: 18px; }
.list li::before {
  content: "";
  position: absolute;
  left: 2px;
  top: .72em;
  width: 6px;
  height: 6px;
  border-radius: 2px;
  background: var(--line-strong);
}
.list.brk li::before { background: var(--break); border-radius: 50%; }
.list.acc li::before { background: var(--accent); }

.note {
  margin: 18px 0 0;
  padding: 14px 16px 14px 18px;
  border-radius: var(--radius-sm);
  border: 1px dashed var(--line-strong);
  font-size: 14.5px;
  color: var(--ink-2);
}
.note b { color: var(--ink); }

/* 표 */
.tbl {
  width: 100%;
  overflow-x: auto;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background: var(--bg-elev);
  -webkit-overflow-scrolling: touch;
}
.tbl table { width: 100%; border-collapse: collapse; font-size: 14.5px; min-width: 620px; }
.tbl th, .tbl td { padding: 12px 16px; text-align: left; vertical-align: top; }
.tbl thead th {
  font-size: 12.5px;
  font-weight: 700;
  color: var(--muted);
  background: var(--bg-sunk);
  border-bottom: 1px solid var(--line);
  white-space: nowrap;
}
.tbl tbody tr + tr td { border-top: 1px solid var(--line); }
.tbl td:first-child { font-weight: 650; }
.tbl td.nowrap, .tbl th.nowrap { white-space: nowrap; }
.tbl td .muted, .tbl small { color: var(--muted); }
.tbl a { color: var(--accent); }
.tbl .shallow { color: var(--muted); }
.tbl .deep { color: var(--ink); }

/* ---------- 히어로 ---------- */
.hero {
  position: relative;
  padding: 72px 0 76px;
  overflow: hidden;
  border-bottom: 1px solid var(--line);
}
.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--line) 1px, transparent 1px),
    linear-gradient(90deg, var(--line) 1px, transparent 1px);
  background-size: 32px 32px;
  mask-image: radial-gradient(ellipse 70% 60% at 78% 42%, #000 0%, transparent 75%);
  -webkit-mask-image: radial-gradient(ellipse 70% 60% at 78% 42%, #000 0%, transparent 75%);
  opacity: .55;
  pointer-events: none;
}
.hero-grid {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1.02fr) minmax(0, .98fr);
  gap: 52px;
  align-items: center;
}
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 18px;
  font-size: 13.5px;
  font-weight: 650;
  color: var(--accent);
}
.lv-badge {
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .06em;
  padding: 3px 9px;
  border-radius: 999px;
  color: var(--accent-ink);
  background: var(--accent);
}
.hero h1 {
  font-size: clamp(2.3rem, 5vw, 3.5rem);
  font-weight: 850;
  letter-spacing: -0.035em;
  line-height: 1.15;
  margin-bottom: 22px;
}
.hero h1 .hl {
  background: linear-gradient(transparent 62%, var(--accent-soft) 62%);
  padding: 0 2px;
}
.lead {
  font-size: 1.1rem;
  color: var(--ink-2);
  line-height: 1.78;
  max-width: 37em;
}
.lead b { color: var(--ink); }
.cta { display: flex; flex-wrap: wrap; gap: 10px; margin: 28px 0 34px; }

.facts {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--bg-elev);
  overflow: hidden;
}
.facts div { padding: 14px 16px; }
.facts div + div { border-left: 1px solid var(--line); }
.facts dt { font-size: 1.45rem; font-weight: 800; letter-spacing: -0.02em; line-height: 1.2; }
.facts dd { margin: 4px 0 0; font-size: 12.5px; color: var(--muted); line-height: 1.45; }

/* 요청 경로 실패 지도 */
.failmap {
  position: relative;
  padding: 20px 20px 18px;
  border-radius: 18px;
  background: var(--bg-elev);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
}
.failmap-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 14px;
  font-size: 13px;
  color: var(--muted);
}
.failmap-head { flex-wrap: wrap; }
.failmap-head b { color: var(--ink); font-size: 14px; white-space: nowrap; }
.fm-path { list-style: none; display: grid; gap: 0; }
.fm-layer {
  --c: var(--c-app);
  position: relative;
  display: grid;
  grid-template-columns: 54px minmax(0, 1fr) auto;
  gap: 12px;
  align-items: center;
  padding: 10px 12px;
  border-radius: 11px;
  border: 1px solid color-mix(in srgb, var(--c) 30%, var(--line));
  background: color-mix(in srgb, var(--c) 7%, var(--bg-elev));
}
.fm-layer + .fm-layer, .fm-layer + .fm-branch, .fm-branch + .fm-layer { margin-top: 14px; }
.fm-layer + .fm-layer::before, .fm-branch + .fm-layer::before {
  content: "";
  position: absolute;
  left: 38px;
  top: -15px;
  width: 2px;
  height: 14px;
  background: var(--line-strong);
}
.fm-k {
  font-family: var(--mono);
  font-size: 10.5px;
  font-weight: 700;
  letter-spacing: .05em;
  color: var(--c);
}
.fm-t b { display: block; font-size: 14px; font-weight: 720; line-height: 1.35; }
.fm-t span { display: block; font-size: 12px; color: var(--muted); line-height: 1.45; }
.fm-marks { display: flex; gap: 4px; }
.fm-layer.web { --c: var(--c-web); }
.fm-layer.dns { --c: var(--c-dns); }
.fm-layer.edge { --c: var(--c-edge); }
.fm-layer.app { --c: var(--c-app); }
.fm-layer.db { --c: var(--c-db); }
.fm-layer.mq { --c: var(--c-mq); }
.fm-layer.ws { --c: var(--c-ws); }
.fm-branch {
  position: relative;
  margin-left: 30px;
}
.fm-branch .fm-layer { padding: 8px 12px; }
.fm-branch::before {
  content: "";
  position: absolute;
  left: -20px;
  top: -14px;
  width: 16px;
  height: calc(50% + 14px);
  border-left: 2px solid var(--line-strong);
  border-bottom: 2px solid var(--line-strong);
  border-bottom-left-radius: 8px;
}
.fm-cross {
  margin-top: 14px;
  padding: 10px 12px;
  border-radius: 11px;
  border: 1px dashed var(--line-strong);
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  font-size: 12.5px;
  color: var(--muted);
}
.fm-cross .fm-marks { order: -1; }
.failmap-foot { margin-top: 12px; font-size: 12.5px; color: var(--muted); }
.failmap-foot .mark { width: 16px; height: 16px; font-size: 9px; box-shadow: none; vertical-align: -3px; margin-right: 4px; }

/* ---------- 개요 ---------- */
.ability { display: flex; flex-direction: column; }
.ability .num { color: var(--accent); }
.rule-card { border-top: 3px solid var(--break); }
.rule-card .num { color: var(--break); }

/* ---------- Level 1 → Level 2 ---------- */
.ladder {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 44px minmax(0, 1fr);
  align-items: stretch;
  gap: 0;
}
.lv-card {
  padding: 24px;
  border-radius: var(--radius);
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-top: 3px solid var(--l1);
}
.lv-card.l2 { border-top-color: var(--accent); }
.lv-card .lv-k {
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .06em;
  color: var(--l1);
}
.lv-card.l2 .lv-k { color: var(--accent); }
.lv-card h3 { font-size: 1.2rem; font-weight: 780; margin: 8px 0 14px; }
.lv-card dl { margin: 0; display: grid; grid-template-columns: 64px minmax(0, 1fr); gap: 8px 12px; font-size: 14.5px; }
.lv-card dt { color: var(--muted); font-weight: 600; }
.lv-card dd { margin: 0; color: var(--ink-2); }
.ladder-arrow { display: grid; place-items: center; color: var(--muted); font-size: 22px; }

.link-tbl td:nth-child(2), .link-tbl td:nth-child(3) { color: var(--ink-2); }
.link-tbl td:first-child { white-space: nowrap; }
.link-tbl .chips { margin-top: 6px; }

/* ---------- 10단계 ---------- */
.flow {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 22px;
}
.flow a {
  display: inline-grid;
  place-items: center;
  min-width: 34px;
  height: 34px;
  padding: 0 8px;
  border-radius: 9px;
  border: 1px solid var(--line);
  background: var(--bg-elev);
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 700;
  text-decoration: none;
  color: var(--ink);
}
.flow a:hover { border-color: var(--accent); color: var(--accent); }
.flow a.st-writing { border-color: color-mix(in srgb, var(--warn) 50%, var(--line)); }
.flow .ar { color: var(--muted); font-size: 13px; }
.flow .par {
  display: inline-flex;
  gap: 4px;
  padding: 3px;
  border-radius: 11px;
  border: 1px dashed var(--line-strong);
}
.flow .par i { font-style: normal; color: var(--muted); font-size: 12px; align-self: center; }
.stage-tools { display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap; margin-bottom: 14px; }
.stage-tools p { margin: 0; color: var(--muted); font-size: 14px; }

.stages { display: grid; gap: 12px; }
.stage {
  border-radius: var(--radius);
  background: var(--bg-elev);
  border: 1px solid var(--line);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  scroll-margin-top: calc(var(--nav-h) + 16px);
}
.stage[open] { box-shadow: var(--shadow); border-color: var(--line-strong); }
.stage > summary {
  list-style: none;
  cursor: pointer;
  display: grid;
  grid-template-columns: 58px minmax(0, 1fr) auto;
  gap: 16px;
  align-items: start;
  padding: 18px 20px;
}
.stage > summary::-webkit-details-marker { display: none; }
.st-num {
  font-family: var(--mono);
  font-size: 1.55rem;
  font-weight: 800;
  line-height: 1.1;
  color: var(--accent);
  letter-spacing: -0.03em;
}
.stage.lab .st-num, .stage.final .st-num { font-size: 1.05rem; padding-top: 6px; }
.st-title { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.st-title h3 { font-size: 1.12rem; font-weight: 780; }
.st-one { margin: 6px 0 8px; color: var(--ink-2); font-size: 15px; }
.st-side { display: flex; align-items: center; gap: 10px; padding-top: 4px; }
.st-chev {
  width: 26px; height: 26px; display: grid; place-items: center;
  border-radius: 8px; border: 1px solid var(--line); color: var(--muted);
  transition: transform .2s;
}
.stage[open] .st-chev { transform: rotate(180deg); }
.st-body {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 22px 28px;
  padding: 4px 20px 20px 94px;
}
.st-body h4 {
  font-size: 12.5px;
  font-weight: 700;
  letter-spacing: .02em;
  color: var(--muted);
  margin: 0 0 8px;
}
.st-body h4.brk { color: var(--break); }
.st-body h4.acc { color: var(--accent); }
.st-body .list { font-size: 14.5px; gap: 6px; }
.st-pass {
  grid-column: 1 / -1;
  padding: 14px 16px;
  border-radius: var(--radius-sm);
  background: var(--accent-soft);
  color: var(--ink);
  font-size: 14.5px;
}
.st-pass b { color: var(--accent); margin-right: 6px; }
.st-foot {
  grid-column: 1 / -1;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  padding-top: 12px;
  border-top: 1px dashed var(--line);
  font-size: 14px;
  color: var(--muted);
}
.st-foot a { color: var(--accent); font-weight: 650; text-decoration: none; }
.st-foot a:hover { text-decoration: underline; text-underline-offset: 3px; }
.st-links { display: flex; gap: 14px; flex-wrap: wrap; }

/* ---------- MiniTrade ---------- */
.model .card h4 { display: flex; align-items: center; gap: 8px; }
.model .card h4 i { width: 10px; height: 10px; border-radius: 3px; background: var(--c, var(--accent)); }

.arch {
  margin-top: 18px;
  padding: 24px;
  border-radius: 18px;
  background: var(--bg-elev);
  border: 1px solid var(--line);
  box-shadow: var(--shadow-sm);
}
.arch-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px 22px;
  align-items: stretch;
}
.ab {
  --c: var(--c-app);
  position: relative;
  padding: 12px 14px;
  border-radius: 12px;
  border: 1px solid color-mix(in srgb, var(--c) 35%, var(--line));
  background: color-mix(in srgb, var(--c) 8%, var(--bg-elev));
}
.ab .k { font-family: var(--mono); font-size: 10.5px; font-weight: 700; letter-spacing: .05em; color: var(--c); }
.ab b { display: block; font-size: 14.5px; font-weight: 720; margin: 2px 0 2px; }
.ab span { display: block; font-size: 12.5px; color: var(--muted); line-height: 1.45; }
.ab.web { --c: var(--c-web); }
.ab.edge { --c: var(--c-edge); }
.ab.app { --c: var(--c-app); }
.ab.ws { --c: var(--c-ws); }
.ab.db { --c: var(--c-db); }
.ab.mq { --c: var(--c-mq); }
.ab.ext { --c: var(--muted); border-style: dashed; }
.ab.obs { --c: var(--accent); }
.arch-col { display: grid; gap: 14px; align-content: start; }
.arch-col .lbl {
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 700;
  color: var(--muted);
  letter-spacing: .06em;
}
.arch-obs { grid-column: 1 / -1; display: flex; align-items: center; gap: 12px; }
.arch-obs .ab { flex: 1; }
.arch-arrows { font-size: 12.5px; color: var(--muted); margin-top: 14px; }
.arch-arrows code { font-size: 12px; }

/* ---------- 랩 환경 ---------- */
.mode-card { border-top: 3px solid var(--accent); }
.mode-card.real { border-top-color: var(--warn); }
.mode-card .k { font-family: var(--mono); font-size: 12px; font-weight: 700; color: var(--accent); letter-spacing: .05em; }
.mode-card.real .k { color: var(--warn); }
.mode-card h3 { margin: 6px 0 10px; }

details.fold {
  margin-top: 16px;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background: var(--bg-elev);
}
details.fold > summary {
  cursor: pointer;
  list-style: none;
  padding: 14px 18px;
  font-weight: 700;
  display: flex;
  justify-content: space-between;
  gap: 12px;
}
details.fold > summary::-webkit-details-marker { display: none; }
details.fold > summary::after { content: "펼치기"; font-size: 13px; color: var(--muted); font-weight: 500; }
details.fold[open] > summary::after { content: "접기"; }
details.fold > .tbl { border: 0; border-top: 1px solid var(--line); border-radius: 0 0 var(--radius) var(--radius); }

/* ---------- 산출물 · 일정 ---------- */
.out-card { display: flex; flex-direction: column; gap: 12px; }
.out-card .chips .chip { font-family: var(--mono); color: var(--accent); background: var(--accent-soft); }
.out-card .crit { font-size: 14px; color: var(--ink-2); padding-top: 12px; border-top: 1px dashed var(--line); }
.out-card .crit b { display: block; font-size: 12.5px; color: var(--muted); margin-bottom: 4px; }

.alloc {
  display: grid;
  grid-template-columns: 2fr 6fr 2fr 1fr;
  border-radius: 10px;
  overflow: hidden;
  border: 1px solid var(--line);
  margin-top: 10px;
}
.alloc div { padding: 10px 12px; font-size: 13px; line-height: 1.35; background: var(--bg-elev); }
.alloc div + div { border-left: 1px solid var(--line); }
.alloc b { display: block; font-size: 15px; }
.alloc .a1 { background: color-mix(in srgb, var(--c-app) 9%, var(--bg-elev)); }
.alloc .a2 { background: color-mix(in srgb, var(--accent) 10%, var(--bg-elev)); }
.alloc .a3 { background: color-mix(in srgb, var(--break) 9%, var(--bg-elev)); }
.alloc .a4 { background: color-mix(in srgb, var(--warn) 10%, var(--bg-elev)); }

.progress { display: grid; gap: 8px; }
.prog-row {
  display: grid;
  grid-template-columns: 56px minmax(0, 1fr) auto;
  gap: 12px;
  align-items: center;
  padding: 10px 14px;
  border-radius: 10px;
  background: var(--bg-elev);
  border: 1px solid var(--line);
  font-size: 14.5px;
  text-decoration: none;
}
.prog-row:hover { border-color: var(--line-strong); }
.prog-row .k { font-family: var(--mono); font-weight: 700; color: var(--accent); }

/* ---------- 사실 확인 ---------- */
.verdict { font-weight: 700; white-space: nowrap; }
.verdict.ok { color: var(--ok); }
.verdict.fix { color: var(--warn); }
.verdict.later { color: var(--muted); }

/* ---------- 바닥글 ---------- */
.footer { padding: 56px 0 64px; font-size: 14.5px; color: var(--muted); }
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr; gap: 32px; }
.footer b { color: var(--ink); }
.footer p { margin: 0 0 8px; }
.footer a { color: var(--ink-2); }
.footer ul { list-style: none; display: grid; gap: 6px; }

/* ---------- 반응형 ---------- */
@media (max-width: 1120px) {
  .nav-links a { padding: 6px 8px; font-size: 14px; }
}

@media (max-width: 1020px) {
  :root { --nav-h: 56px; }
  .menu-btn { display: inline-grid; }
  .nav-links {
    position: absolute;
    top: var(--nav-h);
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    padding: 8px var(--gutter) 14px;
    background: var(--bg);
    border-bottom: 1px solid var(--line);
    box-shadow: var(--shadow);
    display: none;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 11px 6px; font-size: 15.5px; border-radius: 8px; }
  .nav-actions { margin-left: auto; }

  .hero-grid { grid-template-columns: minmax(0, 1fr); gap: 40px; }
  .grid.c4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .arch-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 860px) {
  .section { padding: 72px 0; }
  .grid.c3, .grid.c2 { grid-template-columns: minmax(0, 1fr); }
  .ladder { grid-template-columns: minmax(0, 1fr); }
  .ladder-arrow { height: 40px; transform: rotate(90deg); }
  .st-body { grid-template-columns: minmax(0, 1fr); padding: 4px 20px 20px; }
}

@media (max-width: 640px) {
  :root { --gutter: 16px; }
  body { font-size: 16px; }
  .hero { padding: 44px 0 52px; }
  .facts { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .facts div:nth-child(3) { border-left: 0; }
  .facts div:nth-child(n+3) { border-top: 1px solid var(--line); }
  .grid.c4 { grid-template-columns: minmax(0, 1fr); }
  .arch-grid { grid-template-columns: minmax(0, 1fr); }
  .arch { padding: 16px; }
  .fm-layer { grid-template-columns: 44px minmax(0, 1fr); }
  .fm-marks { grid-column: 2; }
  .fm-layer + .fm-layer::before, .fm-branch + .fm-layer::before { left: 30px; }
  .fm-branch { margin-left: 22px; }
  .stage > summary { grid-template-columns: 44px minmax(0, 1fr); padding: 16px; gap: 12px; }
  .st-side { grid-column: 1 / -1; justify-content: space-between; padding-top: 0; }
  .st-num { font-size: 1.3rem; }
  .st-body { padding: 0 16px 18px; }
  .lv-card dl { grid-template-columns: minmax(0, 1fr); gap: 2px; }
  .lv-card dd { margin-bottom: 8px; }
  .alloc { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .alloc div:nth-child(3) { border-left: 0; }
  .alloc div:nth-child(n+3) { border-top: 1px solid var(--line); }
  .footer-grid { grid-template-columns: minmax(0, 1fr); gap: 20px; }
  .prog-row { grid-template-columns: 44px minmax(0, 1fr); }
  .prog-row .badge { grid-column: 2; justify-self: start; }
  .brand .brand-text { display: none; }
}

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

@media print {
  .nav, .cta, .menu-btn, .theme-btn, .stage-tools .btn { display: none !important; }
  .section { padding: 28px 0; }
  .stage .st-body { display: grid !important; }
}