:root {
  --sand: #e8dfd2;
  --sand-deep: #d9cbb8;
  --paper: #f3ebe0;
  --ink: #1b2433;
  --navy: #1a2a44;
  --navy-soft: #2a3f61;
  --muted: #5a6578;
  --line: #c9bba8;
  --accent: #1a2a44;
  --soft: #fffaf3;
  --max: 1040px;
  --radius: 12px;
  font-family: "Source Serif 4", "Noto Serif SC", "Songti SC", "SimSun", serif;
}

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

html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--ink);
  background:
    linear-gradient(180deg, var(--paper) 0%, var(--sand) 45%, #e2d6c6 100%);
  line-height: 1.8;
  min-height: 100vh;
}

a { color: var(--navy-soft); text-underline-offset: 3px; }
a:hover { color: var(--navy); }

img { max-width: 100%; height: auto; display: block; }

.wrap { width: min(100% - 2rem, var(--max)); margin-inline: auto; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: rgba(243, 235, 224, 0.94);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(8px);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.75rem 0;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  color: var(--navy);
  text-decoration: none;
  font-weight: 700;
  letter-spacing: 0.03em;
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
}
.brand img {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  object-fit: cover;
}

.nav-desktop {
  display: flex;
  gap: 1.15rem;
  flex-wrap: wrap;
  font-family: "Noto Sans SC", "Microsoft YaHei", sans-serif;
}
.nav-desktop a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.92rem;
}
.nav-desktop a:hover { color: var(--navy); }

.menu-toggle {
  display: none;
  background: var(--navy);
  color: var(--sand);
  border: 0;
  border-radius: 8px;
  padding: 0.4rem 0.75rem;
  font: inherit;
  cursor: pointer;
}

#mobile-nav {
  display: none;
  flex-direction: column;
  gap: 0.25rem;
  padding: 0 0 0.85rem;
  font-family: "Noto Sans SC", "Microsoft YaHei", sans-serif;
}
#mobile-nav.open { display: flex; }
#mobile-nav a {
  color: var(--navy);
  text-decoration: none;
  padding: 0.45rem 0.35rem;
  border-bottom: 1px solid var(--line);
}

.ads-slot { border-bottom: 1px solid var(--line); }
.ads-slot .ads-wrap {
  background: var(--soft) !important;
  border-color: var(--line) !important;
  border-radius: var(--radius) !important;
}

/* cascade hero */
.cascade-hero {
  background: var(--navy);
  color: var(--sand);
  padding: 1.35rem 0 1.5rem;
  margin-bottom: 0.5rem;
}
.cascade-hero h1 {
  margin: 0 0 0.55rem;
  font-size: clamp(1.35rem, 3.4vw, 1.95rem);
  line-height: 1.35;
  font-weight: 700;
  max-width: 22em;
}
.cascade-hero .lead {
  margin: 0;
  color: #c5d0e0;
  max-width: 46em;
  font-size: 1.02rem;
  font-family: "Noto Sans SC", "Microsoft YaHei", sans-serif;
}

/* zig sections */
.cascade-body {
  padding: 1.5rem 0 3rem;
  display: flex;
  flex-direction: column;
  gap: 3.25rem;
}

.zig-section {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2.25rem;
  align-items: center;
}
.zig-section.flip .zig-text { order: 2; }
.zig-section.flip .zig-media { order: 1; }

.zig-text h2 {
  margin: 0 0 0.75rem;
  font-size: 1.35rem;
  color: var(--navy);
  line-height: 1.35;
}
.zig-text p {
  margin: 0 0 0.85rem;
  color: var(--ink);
}
.zig-text .eyebrow {
  display: inline-block;
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--navy-soft);
  margin-bottom: 0.45rem;
  font-family: "Noto Sans SC", "Microsoft YaHei", sans-serif;
}

.zig-media figure {
  margin: 0;
  background: var(--soft);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 18px 40px rgba(26, 42, 68, 0.08);
}
.zig-media figcaption {
  padding: 0.55rem 0.75rem 0.7rem;
  font-size: 0.88rem;
  color: var(--muted);
  font-family: "Noto Sans SC", "Microsoft YaHei", sans-serif;
}

.prose-band {
  max-width: 68ch;
  margin: 0 auto;
  padding: 0.5rem 0;
}
.prose-band h2 {
  color: var(--navy);
  font-size: 1.3rem;
  margin: 0 0 0.7rem;
}
.prose-band p { margin: 0 0 0.85rem; }

.peer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem 1rem;
  align-items: center;
  margin: 1.5rem 0;
  padding: 0.9rem 1rem;
  background: var(--soft);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  font-family: "Noto Sans SC", "Microsoft YaHei", sans-serif;
}
.peer-links a { font-weight: 600; }

.faq details {
  border-bottom: 1px solid var(--line);
  padding: 0.35rem 0;
}
.faq summary {
  cursor: pointer;
  color: var(--navy);
  font-weight: 600;
  padding: 0.45rem 0;
  font-family: "Noto Sans SC", "Microsoft YaHei", sans-serif;
}
.faq details p { margin: 0 0 0.75rem; color: var(--muted); }

ul.soft-list {
  margin: 0.4rem 0 1rem;
  padding-left: 1.2rem;
  color: var(--muted);
}
ul.soft-list li { margin-bottom: 0.35rem; }

.site-footer {
  border-top: 1px solid var(--line);
  background: var(--navy);
  color: #b8c4d6;
  padding: 1.4rem 0 1.8rem;
  font-family: "Noto Sans SC", "Microsoft YaHei", sans-serif;
  font-size: 0.9rem;
}
.site-footer a { color: var(--sand); text-decoration: none; }
.footer-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.1rem;
  margin-bottom: 0.6rem;
}

.page-hero { padding: 1.5rem 0 0.5rem; }
.page-hero h1 { color: var(--navy); margin: 0 0 0.4rem; }
.page-hero .muted { color: var(--muted); margin: 0 0 1rem; }
.prose { max-width: 68ch; padding-bottom: 2.5rem; }
.prose h2 { color: var(--navy); }
.err-box { padding: 3.5rem 0; text-align: center; }
.err-box h1 { color: var(--navy); }
.btn {
  display: inline-block;
  margin-top: 0.5rem;
  padding: 0.5rem 1rem;
  background: var(--navy);
  color: var(--sand);
  text-decoration: none;
  border-radius: 8px;
  font-family: "Noto Sans SC", "Microsoft YaHei", sans-serif;
}

@media (max-width: 860px) {
  .nav-desktop { display: none; }
  .menu-toggle { display: inline-block; }
  .zig-section,
  .zig-section.flip {
    grid-template-columns: 1fr;
    gap: 1.15rem;
  }
  .zig-section.flip .zig-text,
  .zig-section.flip .zig-media { order: initial; }
  .cascade-body { gap: 2.4rem; }
}

/* SEO keyword highlight */
strong.kw, .kw{color:var(--accent,var(--brand,#c43b2c));font-weight:700}
mark.kw{background:rgba(196,59,44,.12);color:inherit;padding:0 .15em;border-radius:3px}