/* MeshNetworks.com — educational guide (same layout family, teal accent) */
:root {
  --brand: #0f6b62;
  --brand-dark: #0a4540;
  --brand-soft: #e5f4f2;
  --ink: #1c2430;
  --muted: #4a5568;
  --line: #d3e2df;
  --bg: #f3f7f6;
  --card: #ffffff;
  --radius: 12px;
  --shadow: 0 8px 24px rgba(10, 69, 64, 0.08);
  --max: 1120px;
  --rail: 300px;
  --font: "Segoe UI", system-ui, -apple-system, Roboto, Helvetica, Arial, sans-serif;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font);
  color: var(--ink);
  background: var(--bg);
  line-height: 1.65;
  font-size: 1.05rem;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--brand); }
a:hover { color: var(--brand-dark); }
.container { width: min(100% - 2rem, var(--max)); margin-inline: auto; }

.site-header {
  background: #fff;
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 100;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.75rem 0;
  flex-wrap: wrap;
}
.logo {
  font-weight: 700;
  font-size: 1.15rem;
  text-decoration: none;
  color: var(--ink);
  letter-spacing: -0.02em;
}
.logo span { color: var(--brand); }
.nav { display: flex; flex-wrap: wrap; gap: 0.35rem 0.9rem; align-items: center; }
.nav a, .nav summary {
  text-decoration: none;
  color: var(--muted);
  font-size: 0.92rem;
  font-weight: 600;
}
.nav a:hover, .nav a[aria-current="page"], .nav summary:hover { color: var(--brand-dark); }
.nav-toggle {
  display: none;
  background: var(--brand-soft);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 0.4rem 0.75rem;
  font: inherit;
  cursor: pointer;
}
.nav-drop { position: relative; }
.nav-drop summary { cursor: pointer; list-style: none; }
.nav-drop summary::-webkit-details-marker { display: none; }
.nav-drop summary::after { content: " ▾"; font-size: 0.75em; }
.nav-drop-panel {
  display: none;
  position: absolute;
  top: 1.6rem;
  right: 0;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 8px;
  min-width: 16rem;
  padding: 0.4rem 0;
  box-shadow: var(--shadow);
  z-index: 20;
}
.nav-drop[open] .nav-drop-panel { display: block; }
.nav-drop-panel a { display: block; padding: 0.35rem 0.85rem; font-weight: 550; }

.hero-banner {
  background: url("../images/banner-bg.svg") center/cover no-repeat, linear-gradient(120deg, #e5f4f2, #f7f6f2);
  border-bottom: 1px solid var(--line);
  padding: 2.25rem 0 2rem;
  text-align: center;
}
.hero-banner h1 {
  margin: 0 0 0.35rem;
  font-size: clamp(1.6rem, 3.6vw, 2.25rem);
  letter-spacing: -0.03em;
  color: var(--ink);
}
.hero-banner .tagline {
  margin: 0;
  font-size: 1.05rem;
  color: var(--brand);
  font-weight: 650;
}
.hero-banner .sub {
  margin: 0.6rem auto 0;
  max-width: 42rem;
  color: var(--muted);
  font-size: 0.98rem;
}

.page-wrap { padding: 2rem 0 3rem; }
.layout {
  display: grid;
  grid-template-columns: 1fr var(--rail);
  gap: 2rem;
  align-items: start;
}
.main-content {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1.75rem 1.75rem 2rem;
  box-shadow: var(--shadow);
}
.main-content h2, .main-content h3 { line-height: 1.25; letter-spacing: -0.02em; }
.main-content h2 { margin-top: 1.75rem; font-size: 1.32rem; color: var(--brand-dark); }
.main-content h3 { margin-top: 1.25rem; font-size: 1.08rem; }
.main-content p, .main-content li { color: var(--ink); }
.main-content ul, .main-content ol { padding-left: 1.25rem; }
.main-content li { margin-bottom: 0.4rem; }
.lead { font-size: 1.08rem; color: var(--muted); }
.sources { font-size: 0.92rem; }
.sources li { margin-bottom: 0.35rem; }
.notice {
  background: #fff8ee;
  border: 1px solid #ead7b8;
  border-radius: 8px;
  padding: 0.85rem 1rem;
  font-size: 0.95rem;
}

.product-rail {
  position: sticky;
  top: 4.5rem;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1rem;
  box-shadow: var(--shadow);
}
.product-rail h2 {
  margin: 0.85rem 0 0.35rem;
  font-size: 1.05rem;
}
.product-rail h2:first-child { margin-top: 0; }
.rail-note {
  margin: 0 0 0.75rem;
  font-size: 0.8rem;
  color: var(--muted);
  line-height: 1.4;
}
.book-card {
  display: flex;
  gap: 0.65rem;
  align-items: flex-start;
  padding: 0.65rem 0;
  border-top: 1px solid var(--line);
}
.book-card:first-of-type { border-top: none; padding-top: 0.15rem; }
.book-card img {
  width: 72px;
  height: auto;
  flex: 0 0 72px;
  border-radius: 4px;
  background: #f4f7f6;
  object-fit: contain;
}
.book-card .pc-title {
  margin: 0 0 0.2rem;
  font-size: 0.84rem;
  line-height: 1.35;
  font-weight: 650;
}
.book-card .pc-title a { text-decoration: none; }
.product-rail .recommend-link {
  font-size: 0.72rem;
  font-weight: 500;
}
.book-card .book-meta {
  margin: 0;
  font-size: 0.78rem;
  color: var(--muted);
  line-height: 1.35;
}

.disclosure, .edu-note {
  background: var(--brand-soft);
  border: 1px solid #c5ddd9;
  border-radius: 8px;
  padding: 0.85rem 1rem;
  font-size: 0.88rem;
  color: var(--muted);
  margin: 1rem 0;
}
.edu-note { background: #f4f8f7; border-color: #d5e4e1; }

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
  gap: 1rem;
  margin: 1.25rem 0;
}
.info-card {
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 1rem;
  background: #fff;
}
.info-card h3 { margin: 0 0 0.4rem; color: var(--brand-dark); font-size: 1.02rem; }
.info-card p { margin: 0 0 0.45rem; font-size: 0.92rem; color: var(--muted); }
.info-card a { font-weight: 650; text-decoration: none; }

.faq details {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 0.75rem 1rem;
  margin-bottom: 0.65rem;
  background: #fff;
}
.faq summary { cursor: pointer; font-weight: 650; color: var(--ink); }
.faq details[open] summary { color: var(--brand-dark); margin-bottom: 0.5rem; }

.site-footer {
  background: #12332f;
  color: #e4efed;
  padding: 2rem 0 1.5rem;
  font-size: 0.9rem;
}
.site-footer a { color: #c5e4df; }
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 1.5rem;
  margin-bottom: 1.25rem;
}
.site-footer h3 { margin: 0 0 0.5rem; font-size: 0.95rem; color: #fff; }
.site-footer ul { list-style: none; padding: 0; margin: 0; }
.site-footer li { margin-bottom: 0.35rem; }
.footer-disclosure {
  border-top: 1px solid #2c524c;
  padding-top: 1rem;
  color: #b7ccc8;
  font-size: 0.82rem;
  line-height: 1.5;
}
.footer-meta { margin-top: 0.75rem; color: #8eada8; font-size: 0.8rem; }

.contact-box {
  background: var(--brand-soft);
  border-radius: 10px;
  padding: 1rem 1.15rem;
  border: 1px solid #c5ddd9;
}
.callout-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
  margin: 1rem 0;
}
.callout-table th, .callout-table td {
  border: 1px solid var(--line);
  padding: 0.45rem 0.6rem;
  text-align: left;
  vertical-align: top;
}
.callout-table th { background: var(--brand-soft); font-weight: 650; }

@media (max-width: 900px) {
  .layout { grid-template-columns: 1fr; }
  .product-rail { position: static; }
  .footer-grid { grid-template-columns: 1fr; }
  .nav-drop-panel { position: static; box-shadow: none; border: none; padding-left: 0.5rem; min-width: 0; }
}
@media (max-width: 640px) {
  .nav-toggle { display: inline-block; }
  .nav { display: none; width: 100%; flex-direction: column; align-items: flex-start; }
  .nav.is-open { display: flex; }
  .main-content { padding: 1.25rem; }
}