*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
:root {
  --blue: #2563eb; --blue-dark: #1d4ed8; --blue-light: #eff6ff;
  --teal: #0d9488; --teal-light: #f0fdfa;
  --text: #0f172a; --text-2: #475569; --text-3: #94a3b8;
  --border: #e2e8f0; --bg: #f8fafc; --white: #ffffff;
  --radius: 12px;
  --shadow: 0 1px 3px rgba(0,0,0,0.07), 0 4px 16px rgba(0,0,0,0.05);
}
body { font-family: 'Inter', -apple-system, sans-serif; background: var(--bg); color: var(--text); line-height: 1.6; }
a { text-decoration: none; color: inherit; }
img { display: block; max-width: 100%; }

/* NAV */
nav { background: var(--white); border-bottom: 1px solid var(--border); position: sticky; top: 0; z-index: 100; }
.nav-inner { max-width: 1140px; margin: 0 auto; padding: 0 24px; height: 60px; display: flex; align-items: center; justify-content: space-between; }
.logo { font-size: 1.25rem; font-weight: 800; color: var(--blue); letter-spacing: -0.5px; }
.logo span { color: var(--text); }
.nav-links { display: flex; gap: 4px; list-style: none; }
.nav-links a { padding: 6px 12px; border-radius: 6px; font-size: 0.875rem; font-weight: 500; color: var(--text-2); transition: background 0.15s, color 0.15s; }
.nav-links a:hover { background: var(--blue-light); color: var(--blue); }
.nav-links a.active { color: var(--blue); font-weight: 600; }
.nav-cta { background: var(--blue) !important; color: var(--white) !important; border-radius: 8px !important; padding: 8px 16px !important; }
.nav-cta:hover { background: var(--blue-dark) !important; }
.nav-mobile-btn { display: none; background: none; border: none; cursor: pointer; font-size: 1.4rem; }

/* PAGE HEADER */
.page-header { padding: 48px 24px 56px; text-align: center; color: white; }
.page-header .breadcrumb { font-size: 0.82rem; color: rgba(255,255,255,0.65); margin-bottom: 12px; }
.page-header h1 { font-size: clamp(1.75rem, 4vw, 2.5rem); font-weight: 800; letter-spacing: -0.5px; }
.page-header p { color: rgba(255,255,255,0.8); margin-top: 10px; font-size: 1rem; max-width: 520px; margin-inline: auto; }
.header-blue { background: linear-gradient(135deg, #1e40af, #2563eb); }
.header-teal { background: linear-gradient(135deg, #0d9488, #0891b2); }
.header-orange { background: linear-gradient(135deg, #c2410c, #ea580c); }
.header-purple { background: linear-gradient(135deg, #6d28d9, #7c3aed); }
.header-slate { background: linear-gradient(135deg, #334155, #475569); }

/* CARDS */
.card { background: var(--white); border-radius: var(--radius); border: 1px solid var(--border); box-shadow: var(--shadow); }
.article-card { background: var(--white); border-radius: var(--radius); border: 1px solid var(--border); overflow: hidden; transition: transform 0.2s, box-shadow 0.2s; display: flex; flex-direction: column; }
.article-card:hover { transform: translateY(-3px); box-shadow: 0 8px 32px rgba(0,0,0,0.1); }
.article-thumb { height: 140px; display: flex; align-items: center; justify-content: center; font-size: 2.8rem; }
.article-body { padding: 18px; flex: 1; display: flex; flex-direction: column; }
.article-tag { display: inline-block; font-size: 0.72rem; font-weight: 600; text-transform: uppercase; letter-spacing: 0.5px; padding: 2px 8px; border-radius: 4px; margin-bottom: 8px; }
.tag-blue { color: var(--blue); background: var(--blue-light); }
.tag-teal { color: var(--teal); background: var(--teal-light); }
.tag-purple { color: #7c3aed; background: #f5f3ff; }
.tag-orange { color: #d97706; background: #fff7ed; }
.article-card h3 { font-size: 0.95rem; font-weight: 700; line-height: 1.4; margin-bottom: 6px; }
.article-card p { font-size: 0.82rem; color: var(--text-2); flex: 1; }
.article-meta { font-size: 0.78rem; color: var(--text-3); margin-top: 10px; }

/* LAYOUT */
.container { max-width: 1140px; margin: 0 auto; padding: 0 24px; }
.section { padding: 64px 24px; }
.section-inner { max-width: 1140px; margin: 0 auto; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; }
.section-header { margin-bottom: 36px; }
.section-header h2 { font-size: 1.6rem; font-weight: 800; letter-spacing: -0.5px; }
.section-header p { color: var(--text-2); margin-top: 8px; }

/* ARTICLE PAGE */
.article-layout { max-width: 1100px; margin: -32px auto 64px; padding: 0 24px; display: grid; grid-template-columns: 1fr 300px; gap: 32px; align-items: start; }
.article-content { background: var(--white); border-radius: var(--radius); border: 1px solid var(--border); box-shadow: var(--shadow); padding: 40px; }
.article-content h1 { font-size: 1.75rem; font-weight: 800; letter-spacing: -0.5px; margin-bottom: 12px; }
.article-content .meta { font-size: 0.82rem; color: var(--text-3); margin-bottom: 28px; padding-bottom: 20px; border-bottom: 1px solid var(--border); display: flex; gap: 16px; }
.article-content h2 { font-size: 1.2rem; font-weight: 700; margin: 32px 0 12px; color: var(--text); }
.article-content h3 { font-size: 1rem; font-weight: 700; margin: 24px 0 8px; }
.article-content p { color: var(--text-2); line-height: 1.8; margin-bottom: 16px; }
.article-content ul, .article-content ol { color: var(--text-2); padding-left: 20px; margin-bottom: 16px; line-height: 1.8; }
.article-content li { margin-bottom: 6px; }
.article-content strong { color: var(--text); }
.callout { background: var(--blue-light); border-left: 4px solid var(--blue); border-radius: 0 8px 8px 0; padding: 14px 18px; margin: 20px 0; font-size: 0.9rem; color: var(--text); }
.callout.green { background: #f0fdf4; border-color: #16a34a; }
.callout.orange { background: #fff7ed; border-color: #ea580c; }
.table-wrap { overflow-x: auto; margin: 20px 0; }
table { width: 100%; border-collapse: collapse; font-size: 0.875rem; }
th { background: var(--bg); padding: 10px 14px; text-align: left; font-weight: 700; border-bottom: 2px solid var(--border); }
td { padding: 10px 14px; border-bottom: 1px solid var(--border); color: var(--text-2); }
tr:hover td { background: var(--bg); }

/* SIDEBAR */
.sidebar { display: flex; flex-direction: column; gap: 20px; position: sticky; top: 80px; }
.sidebar-card { background: var(--white); border-radius: var(--radius); border: 1px solid var(--border); overflow: hidden; }
.sidebar-card-header { padding: 14px 18px; border-bottom: 1px solid var(--border); font-weight: 700; font-size: 0.9rem; }
.sidebar-card-body { padding: 16px 18px; }
.sidebar-link { display: flex; align-items: center; gap: 8px; padding: 8px 0; border-bottom: 1px solid #f1f5f9; font-size: 0.85rem; color: var(--text-2); transition: color 0.15s; }
.sidebar-link:last-child { border-bottom: none; }
.sidebar-link:hover { color: var(--blue); }
.tool-cta { background: var(--blue); color: white; border-radius: 8px; padding: 12px 16px; display: block; text-align: center; font-weight: 700; font-size: 0.875rem; margin-bottom: 8px; transition: background 0.15s; }
.tool-cta:hover { background: var(--blue-dark); color: white; }
.tool-cta.teal { background: var(--teal); }
.tool-cta.teal:hover { background: #0f766e; }

/* FOOTER */
footer { background: #0f172a; color: #94a3b8; padding: 48px 24px 32px; }
.footer-inner { max-width: 1140px; margin: 0 auto; }
.footer-top { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; margin-bottom: 40px; }
.footer-logo { font-size: 1.2rem; font-weight: 800; color: white; margin-bottom: 10px; }
.footer-desc { font-size: 0.85rem; line-height: 1.7; max-width: 240px; }
.footer-col h4 { font-size: 0.875rem; font-weight: 700; color: white; margin-bottom: 14px; }
.footer-col ul { list-style: none; display: flex; flex-direction: column; gap: 8px; }
.footer-col a { font-size: 0.85rem; color: #64748b; transition: color 0.15s; }
.footer-col a:hover { color: white; }
.footer-bottom { border-top: 1px solid #1e293b; padding-top: 24px; display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 12px; }
.footer-bottom p { font-size: 0.8rem; }
.footer-disc { font-size: 0.75rem; color: #475569; max-width: 480px; }

/* CHECKLIST */
.checklist { list-style: none; padding: 0; }
.checklist li { display: flex; align-items: flex-start; gap: 10px; padding: 8px 0; border-bottom: 1px solid #f1f5f9; font-size: 0.9rem; color: var(--text-2); }
.checklist li:last-child { border-bottom: none; }
.checklist li::before { content: '☐'; font-size: 1.1rem; color: var(--blue); flex-shrink: 0; margin-top: 1px; }
.checklist-section { margin-bottom: 28px; }
.checklist-section h3 { font-size: 1rem; font-weight: 700; margin-bottom: 8px; display: flex; align-items: center; gap: 8px; }

/* BTN */
.btn { display: inline-flex; align-items: center; gap: 8px; padding: 12px 24px; border-radius: 10px; font-weight: 700; font-size: 0.9rem; cursor: pointer; border: none; transition: all 0.15s; }
.btn-primary { background: var(--blue); color: white; }
.btn-primary:hover { background: var(--blue-dark); }
.btn-outline { background: transparent; color: var(--blue); border: 2px solid var(--blue); }
.btn-outline:hover { background: var(--blue-light); }

/* RESPONSIVE */
@media (max-width: 960px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .footer-top { grid-template-columns: 1fr 1fr; }
  .article-layout { grid-template-columns: 1fr; }
  .sidebar { position: static; }
  .nav-links { display: none; }
  .nav-mobile-btn { display: block; }
}
@media (max-width: 640px) {
  .grid-4, .grid-3, .grid-2 { grid-template-columns: 1fr; }
  .footer-top { grid-template-columns: 1fr; }
  .article-content { padding: 24px 20px; }
  .section { padding: 48px 16px; }
  .page-header h1 { font-size: 1.5rem; }
  .page-header .breadcrumb { font-size: 0.75rem; white-space: normal; word-break: break-word; }
  .article-content .meta { flex-direction: column; gap: 4px; }
  table { font-size: 0.78rem; }
  th, td { padding: 8px 10px; }
}

/* MOBILE NAV OPEN STATE */
nav { position: relative; }
.nav-links.mobile-open {
  display: flex !important;
  flex-direction: column;
  position: absolute;
  top: 60px;
  left: 0;
  right: 0;
  background: var(--white);
  padding: 12px 20px 20px;
  border-bottom: 1px solid var(--border);
  box-shadow: 0 8px 32px rgba(0,0,0,0.12);
  z-index: 200;
  gap: 2px;
}
.nav-links.mobile-open li { width: 100%; }
.nav-links.mobile-open a {
  display: block;
  padding: 11px 14px !important;
  border-radius: 8px;
  font-size: 0.95rem !important;
  font-weight: 500;
  color: var(--text-2) !important;
}
.nav-links.mobile-open a:hover { background: var(--blue-light) !important; color: var(--blue) !important; }
.nav-links.mobile-open .nav-cta {
  background: var(--blue) !important;
  color: var(--white) !important;
  margin-top: 8px;
  text-align: center;
}
.nav-mobile-btn { font-size: 1.5rem; padding: 4px 8px; border-radius: 6px; transition: background 0.15s; }
.nav-mobile-btn:hover { background: var(--bg); }