/* ============================================
   Làm Chủ Claude — master.aiboss.vn
   AIBOSS Brand System (web variant)
   Navy #0a1929/#102a43 · Gold #c89425/#e6b145 · Cream #faf7f0
   ============================================ */

:root {
  --navy-deep: #0a1929;
  --navy: #102a43;
  --navy-card: #13304d;
  --gold: #c89425;
  --gold-bright: #e6b145;
  --cream: #faf7f0;
  --white: #ffffff;
  --ink: #102a43;
  --muted: #5a6b7d;
  --muted-dark: #aeb6c2;
  --border: rgba(16, 42, 67, 0.10);
  --border-dark: rgba(255, 255, 255, 0.10);
  --shadow: 0 2px 24px rgba(10, 25, 41, 0.07);
}

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

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  font-size: 17px;
  line-height: 1.75;
  color: var(--ink);
  background: var(--cream);
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 { font-family: 'Fraunces', Georgia, serif; }

/* —— VN heading rule: line-height ≥1.45, hero ≥1.55 —— */
h1 { line-height: 1.55; }
h2, h3, h4 { line-height: 1.5; }

a { color: var(--gold); }

/* ============ NAV ============ */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 25, 41, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-dark);
}
.nav-inner {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  gap: 24px;
}
.nav-brand {
  font-family: 'Fraunces', serif;
  font-weight: 700;
  font-size: 1.02rem;
  color: var(--white);
  text-decoration: none;
  white-space: nowrap;
  padding: 14px 0;
}
.nav-brand em { color: var(--gold-bright); font-style: italic; }
.nav-links {
  display: flex;
  gap: 4px;
  overflow-x: auto;
  scrollbar-width: none;
  -ms-overflow-style: none;
}
.nav-links::-webkit-scrollbar { display: none; }
.nav-links a {
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--muted-dark);
  text-decoration: none;
  padding: 16px 10px;
  white-space: nowrap;
  border-bottom: 2px solid transparent;
  transition: color .2s, border-color .2s;
}
.nav-links a:hover { color: var(--white); }
.nav-links a.active { color: var(--gold-bright); border-bottom-color: var(--gold-bright); }

/* ============ HERO ============ */
.hero {
  background:
    radial-gradient(1100px 500px at 80% -10%, rgba(200, 148, 37, 0.16), transparent 60%),
    radial-gradient(800px 420px at 10% 110%, rgba(230, 177, 69, 0.08), transparent 55%),
    linear-gradient(165deg, var(--navy-deep) 0%, var(--navy) 100%);
  color: var(--white);
  padding: 96px 24px 110px;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.hero::after {
  content: "";
  position: absolute;
  inset: auto 0 0 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(230,177,69,.5), transparent);
}
.hero-inner { max-width: 880px; margin: 0 auto; }
.hero .kicker { margin-bottom: 22px; }
.hero h1 {
  font-size: clamp(2.1rem, 6vw, 3.6rem);
  font-weight: 600;
  line-height: 1.55;
  margin-bottom: 26px;
}
.hero h1 em { color: var(--gold-bright); font-style: italic; }
.hero p.sub {
  font-size: clamp(1.02rem, 2.2vw, 1.18rem);
  color: var(--muted-dark);
  max-width: 660px;
  margin: 0 auto 40px;
}
.hero-stats {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 14px 36px;
  margin-bottom: 44px;
}
.hero-stats span {
  font-size: 0.9rem;
  color: var(--muted-dark);
}
.hero-stats strong {
  display: block;
  font-family: 'Fraunces', serif;
  font-size: 1.7rem;
  color: var(--gold-bright);
  line-height: 1.45;
}

/* ============ SECTIONS ============ */
.section { padding: 88px 24px; background: var(--cream); }
.section--dark {
  background: linear-gradient(180deg, var(--navy-deep) 0%, var(--navy) 100%);
  color: #eef2f7;
}
.section--dark .sec-title, .section--dark .sub-title, .section--dark h4 { color: var(--white); }
.section--dark p { color: var(--muted-dark); }
.section--dark .lead { color: #d7dee8; }

.container { max-width: 1080px; margin: 0 auto; }

section[id] { scroll-margin-top: 64px; }

.kicker {
  font-family: 'Inter', sans-serif;
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--gold);
  margin-bottom: 14px;
}
.section--dark .kicker { color: var(--gold-bright); }

.sec-title {
  font-size: clamp(1.7rem, 4vw, 2.5rem);
  font-weight: 600;
  line-height: 1.5;
  margin-bottom: 18px;
}
.sec-title em, .sub-title em, em.gold { color: var(--gold); font-style: italic; }
.section--dark .sec-title em, .section--dark em.gold { color: var(--gold-bright); }

.lead {
  font-size: 1.13rem;
  color: var(--muted);
  max-width: 720px;
  margin-bottom: 40px;
}

.sub-title {
  font-size: 1.32rem;
  font-weight: 600;
  margin: 48px 0 14px;
  display: flex;
  align-items: baseline;
  gap: 12px;
}

.section p + p { margin-top: 14px; }

/* ============ GRID + CARD ============ */
.grid { display: grid; gap: 22px; margin: 36px 0; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }

.card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 28px 26px;
  box-shadow: var(--shadow);
  transition: transform .25s ease, box-shadow .25s ease;
}
.card:hover { transform: translateY(-3px); box-shadow: 0 10px 32px rgba(10,25,41,.10); }
.card h3 {
  font-size: 1.12rem;
  font-weight: 600;
  margin-bottom: 8px;
}
.card h4 { font-size: 1rem; font-weight: 600; margin-bottom: 6px; }
.card p { font-size: 0.95rem; color: var(--muted); }
.card p + p { margin-top: 10px; }
.card-icon { font-size: 1.7rem; margin-bottom: 14px; line-height: 1; }

.section--dark .card {
  background: rgba(255, 255, 255, 0.045);
  border-color: var(--border-dark);
  box-shadow: none;
}
.section--dark .card h3, .section--dark .card h4 { color: var(--white); }
.section--dark .card p { color: var(--muted-dark); }

/* ============ CALLOUT ============ */
.callout {
  background: rgba(200, 148, 37, 0.09);
  border-left: 3px solid var(--gold);
  border-radius: 10px;
  padding: 18px 22px;
  margin: 26px 0;
  font-size: 0.98rem;
}
.callout--warn { background: rgba(200, 90, 37, 0.08); border-left-color: #c05a25; }
.section--dark .callout {
  background: rgba(230, 177, 69, 0.10);
  border-left-color: var(--gold-bright);
  color: #e7ddc8;
}

/* ============ CODE ============ */
.code {
  background: var(--navy-deep);
  color: #e8eef5;
  border: 1px solid rgba(230, 177, 69, 0.18);
  border-radius: 12px;
  padding: 22px 24px;
  margin: 22px 0;
  overflow-x: auto;
  font-family: 'JetBrains Mono', 'SF Mono', Menlo, monospace;
  font-size: 0.84rem;
  line-height: 1.7;
  position: relative;
}
.copy-btn {
  position: absolute;
  top: 10px;
  right: 10px;
  font-family: 'Inter', sans-serif;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--gold-bright);
  background: rgba(230, 177, 69, 0.12);
  border: 1px solid rgba(230, 177, 69, 0.35);
  border-radius: 8px;
  padding: 6px 12px;
  cursor: pointer;
  transition: background .2s, color .2s, border-color .2s;
}
.copy-btn:hover {
  background: linear-gradient(135deg, var(--gold), var(--gold-bright));
  color: var(--navy-deep);
  border-color: transparent;
}
.copy-btn.copied {
  background: var(--gold-bright);
  color: var(--navy-deep);
  border-color: transparent;
}
.code code { font-family: inherit; }
.section--dark .code { background: rgba(0,0,0,.35); }

/* ============ ACCORDION ============ */
.acc {
  border-bottom: 1px solid var(--border);
  padding: 4px 0;
}
.section--dark .acc { border-bottom-color: var(--border-dark); }
.acc summary {
  font-family: 'Fraunces', serif;
  font-size: 1.04rem;
  font-weight: 600;
  line-height: 1.5;
  padding: 16px 36px 16px 4px;
  cursor: pointer;
  list-style: none;
  position: relative;
}
.acc summary::-webkit-details-marker { display: none; }
.acc summary::after {
  content: "+";
  position: absolute;
  right: 8px;
  top: 50%;
  transform: translateY(-50%);
  font-family: 'Inter', sans-serif;
  font-weight: 400;
  font-size: 1.3rem;
  color: var(--gold);
  transition: transform .2s;
}
.acc[open] summary::after { content: "–"; }
.acc[open] summary { color: var(--gold); }
.section--dark .acc[open] summary { color: var(--gold-bright); }
.acc-body { padding: 2px 4px 20px; font-size: 0.96rem; }
.acc-body p { color: var(--muted); }
.section--dark .acc-body p { color: var(--muted-dark); }
.acc-body ul { padding-left: 22px; margin: 8px 0; }
.acc-body li { margin: 5px 0; color: var(--muted); font-size: 0.95rem; }
.section--dark .acc-body li { color: var(--muted-dark); }

/* ============ NUM + STEPS ============ */
.num {
  font-family: 'Fraunces', serif;
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--navy);
  background: linear-gradient(135deg, var(--gold), var(--gold-bright));
  min-width: 34px;
  height: 34px;
  border-radius: 10px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}
.steps { display: flex; flex-direction: column; gap: 20px; margin: 32px 0; }
.step { display: flex; gap: 18px; align-items: flex-start; }
.step h4 { font-size: 1.05rem; margin-bottom: 4px; }
.step p { font-size: 0.95rem; color: var(--muted); }
.section--dark .step p { color: var(--muted-dark); }

/* ============ BUTTON ============ */
.btn {
  display: inline-block;
  background: linear-gradient(135deg, var(--gold), var(--gold-bright));
  color: var(--navy-deep);
  font-family: 'Inter', sans-serif;
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  padding: 14px 30px;
  border-radius: 999px;
  transition: transform .2s, box-shadow .2s;
}
.btn:hover { transform: translateY(-2px); box-shadow: 0 8px 22px rgba(200, 148, 37, 0.35); }
.btn--ghost {
  background: transparent;
  border: 1px solid rgba(230, 177, 69, 0.5);
  color: var(--gold-bright);
}

.divider { height: 44px; }

/* ============ FOOTER ============ */
.footer {
  background: var(--navy-deep);
  color: var(--muted-dark);
  text-align: center;
  padding: 72px 24px 56px;
  border-top: 1px solid var(--border-dark);
}
.footer .signature {
  font-family: 'Pinyon Script', cursive;
  font-size: 2.3rem;
  color: var(--gold-bright);
  margin-bottom: 18px;
  line-height: 1.4;
}
.footer p { font-size: 0.88rem; max-width: 560px; margin: 0 auto 8px; }
.footer a { color: var(--gold-bright); }

/* ============ RESPONSIVE ============ */
@media (max-width: 920px) {
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 640px) {
  body { font-size: 16px; }
  .section { padding: 64px 18px; }
  .hero { padding: 72px 18px 84px; }
  .grid-2, .grid-3 { grid-template-columns: 1fr; }
  .hero-stats { gap: 10px 24px; }
  .nav-inner { padding: 0 14px; gap: 12px; }
}