/* ===== RESET & VARIABLES ===== */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

:root {
  --bg: #f8f7f4;
  --text: #0f172a;
  --text-2: #475569;
  --text-3: #94a3b8;
  --accent: #4F46E5;
  --accent-hover: #4338CA;
  --border: #e2e0dc;
  --border-hover: #ccc9c3;
  --white: #ffffff;
  --serif: 'DM Serif Display', Georgia, serif;
  --sans: 'Inter', -apple-system, sans-serif;
  --mono: 'Space Mono', monospace;
  --max-w: 1140px;
}

html { scroll-behavior: smooth; }
body {
  font-family: var(--sans);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
  background: var(--bg);
}
::selection { background: var(--accent); color: #fff; }

/* ===== NAV ===== */
.nav-wrap {
  position: fixed; top: 16px; left: 50%; transform: translateX(-50%);
  z-index: 200; width: calc(100% - 32px); max-width: 720px;
}
nav {
  background: rgba(255,255,255,0.88);
  backdrop-filter: blur(24px); -webkit-backdrop-filter: blur(24px);
  border: 1px solid var(--border);
  border-radius: 100px;
  padding: 0 8px 0 24px;
  display: flex; justify-content: space-between; align-items: center;
  height: 52px;
  box-shadow: 0 2px 20px rgba(0,0,0,0.04);
}
.nav-logo {
  font-family: var(--serif); font-size: 1.1rem;
  color: var(--text); text-decoration: none; letter-spacing: -0.3px;
}
.nav-logo span { color: var(--accent); }
.nav-center { display: flex; gap: 28px; }
.nav-center a {
  font-family: var(--sans); font-size: 0.82rem; font-weight: 500;
  color: var(--text-2); text-decoration: none; transition: color 0.2s;
}
.nav-center a:hover { color: var(--text); }
.nav-cta {
  font-family: var(--sans); font-size: 0.8rem; font-weight: 600;
  background: var(--text); color: var(--white); text-decoration: none;
  padding: 10px 24px; border-radius: 100px; transition: background 0.2s;
}
.nav-cta:hover { background: #1e293b; }

/* ===== SCROLL REVEAL ===== */
.reveal {
  opacity: 0; transform: translateY(28px);
  transition: opacity 0.7s cubic-bezier(0.16,1,0.3,1), transform 0.7s cubic-bezier(0.16,1,0.3,1);
}
.reveal.visible { opacity: 1; transform: translateY(0); }
.reveal-d1 { transition-delay: 0.1s; }
.reveal-d2 { transition-delay: 0.2s; }
.reveal-d3 { transition-delay: 0.3s; }

/* ===== LABEL ===== */
.label {
  font-family: var(--mono); font-size: 0.68rem; font-weight: 700;
  letter-spacing: 2px; text-transform: uppercase;
  color: var(--accent); margin-bottom: 20px; display: block;
}

/* ===== BREADCRUMB ===== */
.breadcrumb {
  max-width: var(--max-w); margin: 0 auto;
  padding: 100px 24px 0;
  font-family: var(--sans); font-size: 0.78rem;
  color: var(--text-3);
  display: flex; align-items: center; gap: 8px;
}
.breadcrumb a {
  color: var(--text-3); text-decoration: none; transition: color 0.2s;
}
.breadcrumb a:hover { color: var(--text); }
.breadcrumb .sep { color: var(--border); }

/* ===== ARTICLE HERO ===== */
.article-hero {
  max-width: var(--max-w); margin: 0 auto;
  padding: 32px 24px 48px;
}
.article-hero .label { margin-bottom: 16px; }
.article-hero h1 {
  font-family: var(--serif);
  font-size: clamp(2.2rem, 4.5vw, 3.2rem);
  font-weight: 400; line-height: 1.12;
  letter-spacing: -1px; margin-bottom: 18px;
  max-width: 720px;
}
.article-hero .subtitle {
  font-size: 1.08rem; color: var(--text-2); line-height: 1.7;
  max-width: 600px;
}

/* ===== ARTICLE CONTENT ===== */
.article-content {
  max-width: 720px; margin: 0 auto;
  padding: 0 24px 80px;
}
.article-content h2 {
  font-family: var(--serif);
  font-size: 1.65rem; font-weight: 400;
  letter-spacing: -0.3px; line-height: 1.2;
  margin: 56px 0 18px;
}
.article-content h2:first-child { margin-top: 0; }
.article-content h3 {
  font-family: var(--serif);
  font-size: 1.2rem; font-weight: 400;
  letter-spacing: -0.2px; line-height: 1.3;
  margin: 40px 0 12px;
}
.article-content p {
  color: var(--text-2); font-size: 1rem; line-height: 1.8;
  margin-bottom: 20px;
}
.article-content p strong { color: var(--text); font-weight: 600; }
.article-content ul, .article-content ol {
  color: var(--text-2); font-size: 1rem; line-height: 1.8;
  margin-bottom: 20px; padding-left: 24px;
}
.article-content li { margin-bottom: 8px; }
.article-content li strong { color: var(--text); font-weight: 600; }
.article-content a {
  color: var(--accent); text-decoration: underline;
  text-underline-offset: 2px; transition: color 0.2s;
}
.article-content a:hover { color: var(--accent-hover); }
.article-content blockquote {
  border-left: 3px solid var(--accent);
  padding: 16px 24px; margin: 32px 0;
  background: rgba(79,70,229,0.03); border-radius: 0 8px 8px 0;
}
.article-content blockquote p { color: var(--text); margin-bottom: 0; }
.article-content hr {
  border: none; height: 1px; background: var(--border);
  margin: 48px 0; opacity: 0.6;
}
.article-content .highlight-box {
  background: var(--white); border: 1px solid var(--border);
  border-radius: 12px; padding: 28px 32px; margin: 32px 0;
}
.article-content .highlight-box h3 { margin-top: 0; }
.article-content table {
  width: 100%; border-collapse: collapse; margin: 32px 0;
  font-size: 0.92rem;
}
.article-content th {
  text-align: left; font-weight: 600; color: var(--text);
  padding: 12px 16px; border-bottom: 2px solid var(--border);
  font-size: 0.82rem; text-transform: uppercase; letter-spacing: 0.5px;
}
.article-content td {
  padding: 12px 16px; border-bottom: 1px solid var(--border);
  color: var(--text-2);
}
.article-content tr:last-child td { border-bottom: none; }

/* ===== FAQ SECTION ===== */
.faq-section { margin: 56px 0; }
.faq-section h2 { margin-bottom: 24px; }
.faq-item {
  border-bottom: 1px solid var(--border); padding: 20px 0;
}
.faq-item:first-of-type { border-top: 1px solid var(--border); }
.faq-question {
  font-family: var(--sans); font-size: 1rem; font-weight: 600;
  color: var(--text); cursor: pointer; display: flex;
  justify-content: space-between; align-items: center; gap: 16px;
  background: none; border: none; width: 100%; text-align: left;
  padding: 0; line-height: 1.5;
}
.faq-question::after {
  content: '+'; font-family: var(--mono); font-size: 1.2rem;
  color: var(--text-3); flex-shrink: 0; transition: transform 0.2s;
}
.faq-item.open .faq-question::after { content: '\2212'; }
.faq-answer {
  max-height: 0; overflow: hidden; transition: max-height 0.3s ease;
}
.faq-item.open .faq-answer { max-height: 500px; }
.faq-answer p {
  padding-top: 12px; font-size: 0.94rem; color: var(--text-2); line-height: 1.7;
}

/* ===== ARTICLE CTA ===== */
.article-cta {
  text-align: center; padding: 64px 0 0;
  border-top: 1px solid var(--border);
  margin-top: 56px;
}
.article-cta h2 {
  font-family: var(--serif);
  font-size: clamp(1.8rem, 3.5vw, 2.4rem);
  font-weight: 400; letter-spacing: -0.5px; line-height: 1.15;
  margin: 0 0 14px;
}
.article-cta h2 em { font-style: italic; color: var(--accent); }
.article-cta .cta-desc {
  color: var(--text-2); font-size: 1rem; line-height: 1.7;
  max-width: 420px; margin: 0 auto 32px;
}
.article-cta .cta-main-btn {
  display: inline-flex; align-items: center; gap: 10px;
  font-family: var(--sans); font-size: 0.9rem; font-weight: 600;
  background: var(--accent); color: #fff; text-decoration: none;
  padding: 16px 40px; border-radius: 100px;
  transition: all 0.3s cubic-bezier(0.16,1,0.3,1);
}
.article-cta .cta-main-btn:hover {
  background: var(--accent-hover);
  box-shadow: 0 4px 16px rgba(79,70,229,0.25), 0 12px 40px rgba(79,70,229,0.1);
  transform: translateY(-1px);
}
.article-cta .cta-note {
  font-family: var(--mono); font-size: 0.68rem;
  color: var(--text-3); letter-spacing: 0.3px; margin-top: 18px;
}

/* ===== BLOG INDEX ===== */
.blog-grid {
  display: grid; grid-template-columns: repeat(2, 1fr);
  gap: 20px; margin-top: 40px;
}
.blog-card {
  background: var(--white); border: 1px solid var(--border);
  border-radius: 12px; padding: 32px 28px;
  text-decoration: none; color: inherit;
  transition: border-color 0.25s, box-shadow 0.25s;
}
.blog-card:hover {
  border-color: var(--border-hover);
  box-shadow: 0 4px 20px rgba(0,0,0,0.04);
}
.blog-card .blog-card-label {
  font-family: var(--mono); font-size: 0.6rem; font-weight: 700;
  letter-spacing: 1.5px; text-transform: uppercase;
  color: var(--accent); margin-bottom: 12px; display: block;
}
.blog-card h3 {
  font-family: var(--serif); font-size: 1.15rem; font-weight: 400;
  letter-spacing: -0.2px; line-height: 1.3; margin-bottom: 10px;
  color: var(--text);
}
.blog-card p {
  font-size: 0.88rem; color: var(--text-2); line-height: 1.6;
  margin-bottom: 14px;
}
.blog-card .blog-card-date {
  font-family: var(--mono); font-size: 0.62rem;
  color: var(--text-3); letter-spacing: 0.5px;
}

/* ===== INTERNAL LINK CARDS ===== */
.related-pages {
  display: grid; grid-template-columns: repeat(2, 1fr);
  gap: 16px; margin: 40px 0;
}
.related-card {
  background: var(--white); border: 1px solid var(--border);
  border-radius: 10px; padding: 20px 22px;
  text-decoration: none; transition: border-color 0.2s;
  display: block;
}
.related-card:hover { border-color: var(--accent); }
.related-card h4 {
  font-family: var(--serif); font-size: 0.95rem; font-weight: 400;
  color: var(--text); margin-bottom: 4px;
}
.related-card p {
  font-size: 0.78rem; color: var(--text-3); margin-bottom: 0; line-height: 1.4;
}

/* ===== FOOTER ===== */
footer {
  border-top: 1px solid var(--border);
  max-width: var(--max-w); margin: 0 auto;
  padding: 48px 24px;
  display: flex; justify-content: space-between; align-items: flex-start;
}
.footer-logo {
  font-family: var(--serif); font-size: 1.1rem;
  color: var(--text); margin-bottom: 6px;
}
.footer-logo span { color: var(--accent); }
.footer-tagline {
  font-size: 0.82rem; color: var(--text-3);
  max-width: 260px; line-height: 1.5;
}
.footer-copy { font-size: 0.72rem; color: var(--text-3); margin-top: 16px; }
.footer-right { display: flex; gap: 24px; align-items: center; flex-wrap: wrap; }
.footer-right a {
  font-family: var(--mono); font-size: 0.65rem; font-weight: 400;
  letter-spacing: 0.5px; text-transform: uppercase;
  color: var(--text-3); text-decoration: none; transition: color 0.2s;
}
.footer-right a:hover { color: var(--text); }

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
  .nav-center { display: none; }
  nav { padding: 0 6px 0 20px; }
  .breadcrumb { padding-top: 84px; }
  .article-hero h1 { font-size: 2rem; letter-spacing: -0.5px; }
  .article-content h2 { font-size: 1.4rem; margin-top: 40px; }
  .blog-grid { grid-template-columns: 1fr; }
  .related-pages { grid-template-columns: 1fr; }
  footer { flex-direction: column; gap: 20px; }
}