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

:root {
  --ink: #0f172a;
  --body: #334155;
  --muted: #64748b;
  --teal: #0d9488;
  --teal-dark: #0f766e;
  --teal-soft: #f0fdfa;
  --navy: #0f2756;
  --line: rgba(148, 163, 184, 0.24);
  --panel: #f8fafc;
}

body {
  margin: 0;
  font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--ink);
  background: #fff;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--teal-dark); text-decoration: none; }
a:hover { text-decoration: underline; }

.article-nav {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  min-height: 72px;
  padding: 0 clamp(20px, 5vw, 56px);
  background: rgba(255, 255, 255, 0.96);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(16px);
}

.article-logo {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  color: var(--ink);
  text-decoration: none;
}

.article-logo:hover { text-decoration: none; }

.article-logo img { width: 36px; height: 36px; object-fit: contain; }

.article-logo span {
  font-size: 17px;
  line-height: 1;
}

.article-logo .logo-accent { color: #2dd4bf; }

.article-nav-links {
  display: flex;
  align-items: center;
  gap: 22px;
  font-size: 13px;
  font-weight: 700;
}

.article-nav-cta {
  padding: 9px 16px;
  border-radius: 8px;
  background: var(--navy);
  color: #fff;
}

.article-nav-cta:hover { color: #fff; text-decoration: none; background: #1a3d7c; }

main {
  width: min(820px, calc(100% - 40px));
  margin: 0 auto;
  padding: 56px 0 80px;
}

.breadcrumb {
  display: flex;
  gap: 7px;
  flex-wrap: wrap;
  margin-bottom: 28px;
  color: var(--muted);
  font-size: 13px;
}

.article-tag {
  display: inline-flex;
  align-items: center;
  margin-bottom: 18px;
  padding: 6px 13px;
  border: 1px solid rgba(13, 148, 136, 0.22);
  border-radius: 999px;
  background: var(--teal-soft);
  color: var(--teal-dark);
  font-size: 11px;
  font-weight: 900;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1 {
  margin: 0 0 18px;
  font-size: clamp(32px, 6vw, 52px);
  line-height: 1.04;
  letter-spacing: -0.03em;
}

.article-intro {
  margin: 0 0 20px;
  color: var(--body);
  font-size: 19px;
  line-height: 1.75;
}

.article-meta {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 30px;
  color: var(--muted);
  font-size: 14px;
}

.hero-img {
  width: 100%;
  height: auto;
  aspect-ratio: 8 / 5;
  object-fit: cover;
  border-radius: 8px;
  border: 1px solid var(--line);
  margin-bottom: 36px;
  background: var(--panel);
}

.toc, .note, .cta-box, .related-box {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
}

.toc { padding: 22px 24px; margin-bottom: 38px; }
.toc strong { display: block; margin-bottom: 12px; }
.toc ol { margin: 0; padding-left: 20px; color: var(--body); line-height: 1.8; }

.article-body h2 {
  margin: 42px 0 14px;
  font-size: 28px;
  line-height: 1.18;
  letter-spacing: -0.02em;
}

.article-body h3 {
  margin: 28px 0 10px;
  font-size: 20px;
}

.article-body p,
.article-body li {
  color: var(--body);
  font-size: 17px;
  line-height: 1.82;
}

.article-body ul,
.article-body ol {
  padding-left: 24px;
}

.note {
  padding: 18px 20px;
  margin: 26px 0;
  color: var(--body);
}

.cta-box {
  padding: 24px;
  margin: 34px 0;
  background: #f0fdfa;
}

.cta-box h2 { margin-top: 0; }

.cta-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 18px;
}

.btn-primary,
.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 11px 18px;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 800;
}

.btn-primary { background: var(--navy); color: #fff; }
.btn-primary:hover { color: #fff; text-decoration: none; background: #1a3d7c; }
.btn-secondary { border: 1px solid var(--line); background: #fff; color: var(--ink); }
.btn-secondary:hover { text-decoration: none; border-color: rgba(13, 148, 136, 0.45); }

.faq-item {
  padding: 18px 0;
  border-bottom: 1px solid var(--line);
}

.faq-item:last-child { border-bottom: 0; }
.faq-item h3 { margin: 0 0 8px; }
.faq-item p { margin: 0; }

.related-box {
  padding: 24px;
  margin-top: 44px;
}

.related-box h2 { margin-top: 0; }
.related-list { display: grid; gap: 12px; margin-top: 14px; }
.related-list a { font-weight: 800; }

.article-footer {
  border-top: 1px solid var(--line);
  padding: 34px 0;
  color: var(--muted);
  font-size: 13px;
  text-align: center;
}

@media (max-width: 720px) {
  .article-nav { align-items: flex-start; flex-direction: column; padding-block: 14px; }
  .article-nav-links { width: 100%; gap: 14px; overflow-x: auto; padding-bottom: 4px; }
  main { width: min(100% - 32px, 820px); padding-top: 36px; }
  .article-body p, .article-body li { font-size: 16px; }
  .cta-actions { flex-direction: column; }
}