:root {
  /* === Brand (green) — 유지 === */
  --green-50:  #ECFDF5;
  --green-100: #D1FADF;
  --green-200: #A6F4C5;
  --green-500: #22C55E;
  --green-600: #16A34A;
  --green-700: #15803D;
  --green-800: #166534;

  /* === Neutral (slate-based, seed) === */
  --bg:        #FFFFFF;
  --bg-muted:  #F8FAFC;
  --bg-subtle: #F1F5F9;
  --fg:        #0F172A;
  --fg-muted:  #475569;
  --fg-subtle: #64748B;
  --fg-faint:  #94A3B8;
  --border:    #E2E8F0;
  --border-strong: #CBD5E1;

  /* === Surfaces / radii / elevation === */
  --radius-xs: 6px;
  --radius-sm: 8px;
  --radius-md: 10px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-2xl: 20px;

  --shadow-xs: 0 1px 2px rgba(15,23,42,0.04);
  --shadow-sm: 0 1px 2px rgba(15,23,42,0.06), 0 1px 3px rgba(15,23,42,0.04);
  --shadow-md: 0 4px 12px -2px rgba(15,23,42,0.08), 0 2px 4px -2px rgba(15,23,42,0.04);

  --container: 1200px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: "Pretendard Variable", Pretendard, Inter, "Inter Fallback",
               -apple-system, BlinkMacSystemFont, "Apple SD Gothic Neo",
               "Helvetica Neue", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--fg);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  font-feature-settings: "ss01", "cv11";
}

a {
  color: var(--green-700);
  text-decoration: none;
  transition: color 0.15s ease;
}
a:hover { color: var(--green-800); }

/* === Top bar === */
.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255,255,255,0.8);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
}
.topbar-inner {
  max-width: var(--container);
  margin: 0 auto;
  padding: 12px 24px;
  display: flex;
  align-items: center;
  gap: 16px;
}
.topbar .brand {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--fg);
}
.topbar .brand:hover { color: var(--fg); }
.topbar .brand-logo {
  width: 144px;
  height: 26px;
  display: block;
  flex-shrink: 0;
}
.topbar .brand-sub {
  font-weight: 500;
  font-size: 13px;
  color: var(--fg-subtle);
  padding-left: 12px;
  border-left: 1px solid var(--border);
  line-height: 1;
  letter-spacing: -0.01em;
}
.topbar nav {
  margin-left: auto;
  display: flex;
  gap: 2px;
}
.topbar nav a {
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  color: var(--fg-muted);
  font-size: 14px;
  font-weight: 500;
  letter-spacing: -0.01em;
  transition: background 0.15s ease, color 0.15s ease;
}
.topbar nav a:hover {
  background: var(--bg-subtle);
  color: var(--fg);
}

/* === Layout === */
.layout {
  max-width: var(--container);
  margin: 0 auto;
  padding: 32px 24px 48px;
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 48px;
}

/* === Sidebar === */
.sidebar {
  position: sticky;
  top: 80px;
  height: calc(100vh - 100px);
  overflow-y: auto;
  padding-right: 8px;
}
.sidebar h4 {
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--fg-faint);
  margin: 24px 0 8px;
  padding-left: 12px;
}
.sidebar h4:first-child { margin-top: 0; }
.sidebar a {
  display: block;
  padding: 7px 12px;
  border-radius: var(--radius-sm);
  color: var(--fg-muted);
  font-size: 14px;
  font-weight: 500;
  margin-bottom: 1px;
  letter-spacing: -0.01em;
  transition: background 0.15s ease, color 0.15s ease;
}
.sidebar a:hover {
  background: var(--bg-subtle);
  color: var(--fg);
}
.sidebar a.active {
  color: var(--green-700);
  background: var(--green-50);
  font-weight: 600;
}

/* === Main === */
main { min-width: 0; }

section.chapter {
  padding: 32px 0 56px;
  border-bottom: 1px solid var(--border);
}
section.chapter:last-child { border-bottom: none; }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--green-700);
  background: var(--green-50);
  padding: 5px 10px;
  border-radius: 999px;
  margin-bottom: 14px;
}

h1, h2, h3, h4 {
  color: var(--fg);
  letter-spacing: -0.02em;
  font-weight: 600;
}
h1 {
  font-size: 36px;
  line-height: 1.25;
  font-weight: 700;
  margin-bottom: 16px;
  letter-spacing: -0.025em;
}
h2 {
  font-size: 24px;
  line-height: 1.35;
  margin: 32px 0 12px;
}
h3 {
  font-size: 18px;
  line-height: 1.45;
  margin: 24px 0 8px;
}
p {
  color: var(--fg-muted);
  margin-bottom: 12px;
  font-size: 15px;
  line-height: 1.65;
}
ul, ol { color: var(--fg-muted); padding-left: 22px; margin-bottom: 12px; font-size: 15px; }
li { margin-bottom: 6px; line-height: 1.65; }
strong { color: var(--fg); font-weight: 600; }

.lead {
  font-size: 17px;
  color: var(--fg-muted);
  line-height: 1.6;
  margin-bottom: 24px;
  letter-spacing: -0.01em;
}

/* === Hero === */
.hero {
  padding: 0 0 8px;
}
.hero .eyebrow { margin-bottom: 0; }
.hero h1 {
  font-size: 30px;
  line-height: 1.25;
  letter-spacing: -0.025em;
  margin-bottom: 10px;
}
.hero h1 strong { color: var(--green-700); font-weight: 700; }
.hero .lead {
  font-size: 15.5px;
  margin-bottom: 0;
  color: var(--fg-muted);
}
.hero-cta {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--green-600);
  color: white;
  padding: 9px 16px;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 14px;
  letter-spacing: -0.01em;
  transition: background 0.15s ease, transform 0.05s ease;
}
.hero-cta:hover {
  background: var(--green-700);
  color: white;
}
.hero-cta:active { transform: translateY(1px); }

/* === Cards === */
.card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 20px 24px;
  margin-bottom: 16px;
  transition: border-color 0.15s ease;
}
.card:hover { border-color: var(--border-strong); }
.card h3 { margin-top: 0; }

.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 12px; margin: 16px 0 24px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin: 16px 0 24px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; margin: 16px 0 24px; }

.feature {
  background: var(--bg);
  padding: 18px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  transition: border-color 0.15s ease, background 0.15s ease;
}
.feature:hover { border-color: var(--border-strong); background: var(--bg-muted); }
.feature .badge {
  display: inline-grid;
  place-items: center;
  width: 32px; height: 32px;
  background: var(--green-50);
  color: var(--green-700);
  border-radius: var(--radius-md);
  font-weight: 700;
  font-size: 14px;
  margin-bottom: 12px;
}
.feature h3 { margin: 0 0 4px; font-size: 15px; font-weight: 600; }
.feature p { font-size: 13.5px; margin: 0; color: var(--fg-subtle); line-height: 1.55; }

/* === Steps === */
.steps {
  counter-reset: step;
  list-style: none;
  padding: 0;
}
.steps li {
  counter-increment: step;
  position: relative;
  padding-left: 36px;
  margin-bottom: 20px;
}
.steps li::before {
  content: counter(step);
  position: absolute;
  left: 0;
  top: 3px;
  width: 22px;
  height: 22px;
  border-radius: 999px;
  background: var(--green-50);
  color: var(--green-700);
  display: grid;
  place-items: center;
  font-weight: 600;
  font-size: 12px;
  letter-spacing: -0.01em;
}
.steps li h3 { margin: 0 0 4px; font-size: 16px; font-weight: 600; }
.steps li p { margin: 0; }

/* === Screenshots === */
figure { margin: 16px 0 24px; }
figure img {
  width: 100%;
  height: auto;
  display: block;
  border-radius: var(--radius-xl);
  border: 1px solid var(--border);
  background: white;
}
figcaption {
  margin-top: 10px;
  font-size: 13px;
  color: var(--fg-subtle);
  text-align: center;
}

.shot { position: relative; }
.shot .pin {
  position: absolute;
  width: 26px; height: 26px;
  border-radius: 999px;
  background: var(--green-600);
  color: white;
  display: grid; place-items: center;
  font-weight: 700;
  font-size: 12px;
  box-shadow: 0 0 0 4px rgba(34,197,94,0.18), var(--shadow-sm);
  transform: translate(-50%, -50%);
  z-index: 2;
}
.shot .pin::after {
  content: '';
  position: absolute;
  inset: -6px;
  border-radius: 999px;
  border: 2px solid var(--green-600);
  opacity: 0.4;
  animation: pulse 2.4s ease-in-out infinite;
}
@keyframes pulse {
  0%   { transform: scale(1);   opacity: 0.4; }
  70%  { transform: scale(1.6); opacity: 0; }
  100% { transform: scale(1.6); opacity: 0; }
}

/* === Tip / Callout === */
.tip {
  display: flex;
  gap: 12px;
  padding: 14px 16px;
  border-radius: var(--radius-lg);
  background: var(--green-50);
  border: 1px solid var(--green-100);
  color: var(--fg);
  margin: 16px 0 24px;
  font-size: 14.5px;
  line-height: 1.6;
}
.tip .icon { font-size: 18px; line-height: 1.4; }
.tip strong { color: var(--green-800); }

.warn {
  display: flex;
  gap: 12px;
  padding: 14px 16px;
  border-radius: var(--radius-lg);
  background: #FFFBEB;
  border: 1px solid #FDE68A;
  color: var(--fg);
  margin: 16px 0 24px;
  font-size: 14.5px;
  line-height: 1.6;
}
.warn strong { color: #B45309; }

/* === Tag chips === */
.tags { display: flex; flex-wrap: wrap; gap: 6px; margin: 8px 0 16px; }
.tag {
  font-size: 12px;
  padding: 4px 10px;
  background: var(--bg-subtle);
  color: var(--fg-muted);
  border-radius: 999px;
  border: 1px solid var(--border);
  font-weight: 500;
}

/* === Subnav (chips) === */
.subnav { display: flex; flex-wrap: wrap; gap: 6px; margin: 8px 0 24px; }
.subnav a {
  font-size: 13px;
  background: var(--bg-subtle);
  color: var(--fg-muted);
  padding: 6px 12px;
  border-radius: 999px;
  font-weight: 500;
  transition: background 0.15s ease, color 0.15s ease;
}
.subnav a:hover {
  background: var(--green-50);
  color: var(--green-700);
}

/* === Footer === */
footer {
  border-top: 1px solid var(--border);
  margin-top: 48px;
  padding: 32px 24px;
  text-align: center;
  color: var(--fg-subtle);
  font-size: 13px;
}

/* === Responsive === */
@media (max-width: 920px) {
  .layout { grid-template-columns: 1fr; gap: 24px; }
  .sidebar { display: none; }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .hero { padding: 0 0 8px; }
  h1 { font-size: 28px; }
  h2 { font-size: 20px; }
  .topbar nav { display: none; }
  .topbar .brand-sub { display: none; }
}