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

:root {
  --indigo:      #4B3F8A;
  --indigo-dark: #140F29;
  --indigo-mid:  #2A2350;
  --gold:        #D9A820;
  --white:       #FFFFFF;
  --gray:        #F1EFFA;
  --text:        #1A1533;
  --muted:       #4A5568;
  --radius:      16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--text);
  background: var(--white);
  line-height: 1.7;
}

/* ── NAV ─────────────────────────────────────────────────────── */
nav {
  position: sticky; top: 0; z-index: 100;
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 5vw; height: 64px;
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(0,0,0,0.06);
}
.nav-logo {
  display: flex; align-items: center; gap: 10px;
  font-size: 1.25rem; font-weight: 800;
  color: var(--indigo-dark); text-decoration: none; white-space: nowrap;
}
.nav-logo img { width: 32px; height: 32px; border-radius: 8px; }
.logo-text span { color: var(--indigo); }
.nav-links { display: flex; align-items: center; gap: 28px; list-style: none; }
.nav-links a { font-size: 0.9rem; font-weight: 500; color: var(--muted); text-decoration: none; transition: color .2s; }
.nav-links a:hover { color: var(--indigo); }
.nav-cta { background: var(--indigo); color: #fff !important; padding: 8px 18px; border-radius: 20px; }
.nav-cta:hover { background: var(--indigo-dark) !important; }

/* ── HEADER ──────────────────────────────────────────────────── */
.article-header {
  position: relative;
  background: linear-gradient(135deg, var(--indigo-dark) 0%, var(--indigo-mid) 55%, var(--indigo) 100%);
  color: var(--white);
  padding: 56px 5vw 52px;
}
.article-header-inner { max-width: 760px; margin: 0 auto; }
.breadcrumb { font-size: 0.82rem; color: rgba(255,255,255,0.65); margin-bottom: 18px; }
.breadcrumb a { color: rgba(255,255,255,0.8); text-decoration: none; }
.breadcrumb a:hover { color: #fff; }
.article-header h1 {
  font-size: clamp(1.8rem, 4.5vw, 2.8rem);
  font-weight: 900; letter-spacing: -0.02em; line-height: 1.15;
  margin-bottom: 16px;
}
.article-lead { font-size: 1.08rem; color: rgba(255,255,255,0.8); }
.article-meta { margin-top: 18px; font-size: 0.82rem; color: rgba(255,255,255,0.55); }
.accent-bar {
  position: absolute; bottom: 0; left: 0; right: 0; height: 6px;
  background: linear-gradient(to right, var(--indigo) 0%, var(--gold) 50%, var(--indigo) 100%);
}

/* ── ARTICLE BODY ────────────────────────────────────────────── */
.article-body { max-width: 760px; margin: 0 auto; padding: 48px 5vw 32px; }
.article-body h2 {
  font-size: 1.5rem; font-weight: 800; letter-spacing: -0.01em;
  margin: 40px 0 14px; color: var(--indigo-dark);
}
.article-body h3 { font-size: 1.15rem; font-weight: 700; margin: 28px 0 10px; }
.article-body p { margin-bottom: 16px; }
.article-body ul, .article-body ol { margin: 0 0 18px 24px; }
.article-body li { margin-bottom: 8px; }
.article-body a { color: var(--indigo); font-weight: 600; }
.article-body strong { color: var(--indigo-dark); }
.article-body table {
  width: 100%; border-collapse: collapse; margin: 8px 0 24px;
  font-size: 0.93rem; display: block; overflow-x: auto;
}
.article-body th, .article-body td { border: 1px solid #E2DFF0; padding: 10px 12px; text-align: left; vertical-align: top; }
.article-body th { background: var(--gray); font-weight: 700; }
.article-body code, .formula {
  font-family: "SF Mono", ui-monospace, Menlo, Consolas, monospace;
  background: var(--gray); padding: 2px 6px; border-radius: 6px; font-size: 0.9em;
}
.article-body pre {
  background: #150F2E; color: #ece9f7;
  padding: 18px 20px; border-radius: 12px; margin: 8px 0 22px;
  font-family: "SF Mono", ui-monospace, Menlo, Consolas, monospace;
  font-size: 0.88rem; line-height: 1.7; white-space: pre-wrap; overflow-x: auto;
}
.box {
  background: var(--gray); border-left: 4px solid var(--indigo);
  border-radius: 10px; padding: 16px 20px; margin: 8px 0 22px;
}
.box.tip { border-left-color: var(--gold); background: #FFFBEB; }
.box.warn { border-left-color: #E11D48; background: #FFF1F2; }
.box p:last-child, .box ul:last-child { margin-bottom: 0; }
.box-title { font-weight: 800; margin-bottom: 6px; display: block; }

.faq h3 { margin-top: 22px; }

/* ── CTA ─────────────────────────────────────────────────────── */
.cta-box {
  max-width: 760px; margin: 16px auto 0;
  background: linear-gradient(135deg, var(--indigo-dark), var(--indigo));
  color: #fff; border-radius: var(--radius); padding: 30px 28px; text-align: center;
}
.cta-box h2 { font-size: 1.4rem; font-weight: 800; margin-bottom: 8px; color: #fff; }
.cta-box p { color: rgba(255,255,255,0.78); margin-bottom: 20px; }
.btn-primary {
  display: inline-block; background: var(--gold); color: var(--indigo-dark);
  padding: 13px 24px; border-radius: 14px; font-weight: 700; text-decoration: none;
}
.btn-primary:hover { opacity: 0.9; }

/* ── RELATED ─────────────────────────────────────────────────── */
.related { max-width: 760px; margin: 0 auto; padding: 40px 5vw 64px; }
.related h2 { font-size: 1.2rem; font-weight: 800; margin-bottom: 14px; }
.related ul { list-style: none; display: grid; gap: 10px; }
.related a {
  display: block; padding: 14px 18px; border-radius: 12px;
  background: var(--gray); color: var(--indigo-dark);
  text-decoration: none; font-weight: 600;
}
.related a:hover { background: #E6E2F6; }

/* ── INDEX ───────────────────────────────────────────────────── */
.index-body { max-width: 1000px; margin: 0 auto; padding: 48px 5vw 72px; }
.index-body h2 { font-size: 1.35rem; font-weight: 800; margin: 36px 0 16px; color: var(--indigo-dark); }
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 16px; }
.card {
  display: block; background: var(--white); border-radius: var(--radius);
  padding: 20px 22px; text-decoration: none; color: var(--text);
  box-shadow: 0 2px 12px rgba(0,0,0,0.07); transition: transform .2s, box-shadow .2s;
}
.card:hover { transform: translateY(-3px); box-shadow: 0 8px 26px rgba(0,0,0,0.1); }
.card h3 { font-size: 1rem; font-weight: 700; margin-bottom: 6px; color: var(--indigo-dark); }
.card p { font-size: 0.88rem; color: var(--muted); line-height: 1.5; }

/* ── FOOTER ──────────────────────────────────────────────────── */
footer {
  background: var(--text); color: rgba(255,255,255,0.5);
  padding: 36px 5vw; text-align: center; font-size: 0.85rem;
}
footer a { color: rgba(255,255,255,0.65); text-decoration: none; }
footer a:hover { color: #fff; }
.footer-links { display: flex; gap: 24px; justify-content: center; flex-wrap: wrap; margin-bottom: 16px; }
.footer-credit { margin-top: 10px; font-size: 0.8rem; color: rgba(255,255,255,0.4); }
.footer-credit a { color: rgba(255,255,255,0.55); font-weight: 600; }

@media (max-width: 600px) {
  .nav-links { display: none; }
}