:root {
  --navy: #0b2f57;
  --blue: #0284c7;
  --sky: #38bdf8;
  --ink: #102033;
  --muted: #475569;
  --line: #dbe7f0;
  --soft: #f4f8fb;
  --white: #ffffff;
  --green: #0f766e;
  --warn: #b45309;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Arial, sans-serif;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; color: var(--ink); background: var(--white); line-height: 1.68; }
a { color: var(--blue); text-decoration: none; }
a:hover { text-decoration: underline; }
img { max-width: 100%; height: auto; }
code { background: #eef6fc; color: #0b2f57; padding: 2px 6px; border-radius: 4px; font-size: 0.92em; font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace; }
.skip-link { position: absolute; left: -999px; top: 8px; background: var(--navy); color: white; padding: 8px 12px; z-index: 10; border-radius: 4px; }
.skip-link:focus { left: 8px; }
.site-header { position: sticky; top: 0; z-index: 20; background: rgba(255,255,255,.97); border-bottom: 1px solid var(--line); backdrop-filter: blur(10px); }
.header-inner { max-width: 1180px; margin: 0 auto; padding: 12px 20px; display: flex; align-items: center; gap: 18px; justify-content: space-between; }
.brand { display: inline-flex; align-items: center; gap: 10px; color: var(--navy); font-size: 24px; font-weight: 850; letter-spacing: -0.01em; }
.brand:hover { text-decoration: none; }
.brand img { width: 46px; height: 46px; object-fit: contain; display: block; border-radius: 4px; }
.nav { display: flex; flex-wrap: wrap; gap: 14px; align-items: center; font-size: 14px; font-weight: 700; }
.nav a { color: var(--navy); }
.nav .primary { background: var(--navy); color: white; padding: 8px 14px; border-radius: 6px; }
.hero { background: linear-gradient(180deg, #ffffff 0%, #edf8ff 100%); border-bottom: 1px solid var(--line); }
.hero-inner { max-width: 1180px; margin: 0 auto; padding: 54px 20px 36px; display: grid; gap: 30px; grid-template-columns: 1.15fr .85fr; align-items: center; }
.hero h1 { margin: 0 0 14px; color: var(--navy); font-size: clamp(34px, 4.5vw, 56px); line-height: 1.06; letter-spacing: -0.02em; }
.hero p { max-width: 670px; margin: 0 0 22px; color: #30445f; font-size: 18px; }
.hero-actions, .button-row { display: flex; flex-wrap: wrap; gap: 12px; }
.button { display: inline-flex; align-items: center; justify-content: center; min-height: 42px; padding: 10px 16px; border-radius: 6px; border: 1px solid var(--line); background: white; color: var(--navy); font-weight: 800; }
.button.primary { background: var(--blue); color: white; border-color: var(--blue); }
.network-card { background: white; border: 1px solid var(--line); border-radius: 8px; box-shadow: 0 18px 45px rgba(11,47,87,.10); padding: 22px; }
.network-card h2 { margin: 0 0 14px; color: var(--navy); font-size: 20px; }
.signal-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; }
.signal { border: 1px solid var(--line); background: var(--soft); border-radius: 6px; padding: 11px 12px; font-weight: 800; color: var(--navy); font-size: 14px; }
.container { max-width: 1180px; margin: 0 auto; padding: 34px 20px; }
.section-title { display: flex; justify-content: space-between; align-items: end; gap: 18px; margin-bottom: 18px; }
.section-title h2, .page-title h1 { margin: 0; color: var(--navy); line-height: 1.14; }
.section-title p, .page-title p { margin: 8px 0 0; color: var(--muted); max-width: 780px; font-size: 17px; }
.grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
.grid.two { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.card { border: 1px solid var(--line); border-radius: 8px; background: white; padding: 18px; min-height: 100%; display: flex; flex-direction: column; justify-content: space-between; }
.card h3 { margin: 0 0 8px; color: var(--navy); line-height: 1.28; font-size: 18px; }
.card p { color: var(--muted); margin: 0 0 12px; font-size: 15px; }
.meta { color: var(--muted); font-size: 13px; font-weight: 700; margin-bottom: 6px; }
.band { background: var(--soft); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.warning { border-left: 5px solid var(--warn); background: #fff7ed; padding: 14px 16px; border-radius: 6px; color: #713f12; margin: 18px 0; font-size: 15px; }
.takeaways { border-left: 5px solid var(--blue); background: #f0f9ff; padding: 16px 18px; border-radius: 6px; margin: 18px 0; }
.takeaways strong.box-title { display: block; color: var(--navy); font-size: 16px; margin-bottom: 8px; }
.takeaways ul { margin: 0; padding-left: 20px; }
.takeaways li { margin-bottom: 6px; }
.breadcrumbs { font-size: 13px; color: var(--muted); margin-bottom: 14px; }
.layout { display: grid; grid-template-columns: minmax(0, 1fr) 310px; gap: 32px; align-items: start; }
.article { max-width: 820px; }
.article h1 { color: var(--navy); font-size: clamp(28px, 4vw, 42px); line-height: 1.12; margin: 0 0 10px; letter-spacing: -0.015em; }
.article h2 { color: var(--navy); margin-top: 32px; margin-bottom: 12px; line-height: 1.22; font-size: 23px; border-bottom: 1px solid var(--line); padding-bottom: 6px; }
.article h3 { color: var(--navy); margin-top: 20px; margin-bottom: 6px; font-size: 18px; }
.article p.lead { font-size: 18px; color: #1e293b; font-weight: 500; }
.toc, .sidebar-box { border: 1px solid var(--line); border-radius: 8px; padding: 16px; background: white; }
.toc { background: var(--soft); margin: 18px 0; }
.toc ol { margin: 8px 0 0 20px; padding: 0; }
.toc li { margin-bottom: 4px; font-size: 15px; }
.sidebar { position: sticky; top: 84px; display: grid; gap: 16px; }
.sidebar-box strong { display: block; color: var(--navy); margin-bottom: 10px; font-size: 15px; border-bottom: 1px solid var(--line); padding-bottom: 6px; }
.sidebar-box p { margin: 7px 0; font-size: 14px; line-height: 1.4; }
.table-wrap { overflow-x: auto; margin: 16px 0; }
table { width: 100%; border-collapse: collapse; margin: 12px 0; background: white; border: 1px solid var(--line); font-size: 14.5px; }
th, td { padding: 11px 12px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
th { color: var(--navy); background: #edf8ff; font-weight: 800; }
.author-box { border: 1px solid var(--line); background: var(--soft); border-radius: 8px; padding: 16px 18px; margin-top: 32px; font-size: 14px; }
.author-box strong { color: var(--navy); }
.search-bar { display: flex; flex-wrap: wrap; gap: 12px; margin-bottom: 22px; background: var(--soft); padding: 16px; border: 1px solid var(--line); border-radius: 8px; }
.search-bar input, .search-bar select { flex: 1; min-width: 200px; min-height: 42px; padding: 9px 12px; border: 1px solid var(--line); border-radius: 6px; font: inherit; background: white; }
.tool-panel { border: 1px solid var(--line); border-radius: 8px; padding: 20px; background: var(--soft); margin: 18px 0 26px; }
.tool-panel label { display: block; font-weight: 800; color: var(--navy); margin-top: 10px; font-size: 14px; }
.tool-panel input, .tool-panel select, .tool-panel textarea { width: 100%; min-height: 42px; border: 1px solid var(--line); border-radius: 6px; padding: 9px 10px; font: inherit; margin-top: 4px; background: white; }
.tool-panel button { margin-top: 14px; min-height: 42px; border: 0; border-radius: 6px; background: var(--blue); color: white; padding: 10px 18px; font-weight: 800; cursor: pointer; font-size: 15px; }
.tool-panel button:hover { background: var(--navy); }
.result { margin-top: 14px; border: 1px solid #bae6fd; border-radius: 6px; background: #ffffff; padding: 14px 16px; color: var(--navy); }
.footer { background: var(--navy); color: #dbeafe; margin-top: 48px; }
.footer a { color: #f8fafc; }
.footer-inner { max-width: 1180px; margin: 0 auto; padding: 36px 20px; display: grid; grid-template-columns: 1.3fr repeat(3, 1fr); gap: 24px; }
.footer h2, .footer h3 { color: white; margin: 0 0 10px; font-size: 17px; }
.footer p { margin: 0 0 10px; font-size: 14px; line-height: 1.75; }
.small { font-size: 13px; color: var(--muted); }
.footer .small { color: #bfdbfe; }
.diagram-box { margin: 24px 0; padding: 14px; background: #08111d; border: 1px solid #1e3a5f; border-radius: 8px; text-align: center; }
.diagram-box img, .diagram-box svg { max-width: 100%; height: auto; display: block; margin: 0 auto; border-radius: 6px; }
.diagram-box figcaption { margin-top: 10px; font-size: 13.5px; color: #94a3b8; font-weight: 500; line-height: 1.45; }
.not-found { text-align: center; padding: 70px 20px; }
@media (max-width: 860px) {
  .header-inner { align-items: flex-start; flex-direction: column; }
  .hero-inner, .layout, .grid, .grid.two, .footer-inner { grid-template-columns: 1fr; }
  .hero-inner { padding-top: 32px; }
  .sidebar { position: static; }
  .brand { font-size: 22px; }
  .brand img { width: 42px; height: 42px; }
  .nav { gap: 10px; }
  .network-card { box-shadow: none; }
}