:root {
  --ink: #111820;
  --muted: #65717d;
  --steel: #1d2a36;
  --steel-2: #263948;
  --panel: #f4f6f7;
  --paper: #ffffff;
  --line: #d8e0e5;
  --water: #1f78a6;
  --safety: #f0a22e;
  --oxide: #a84f2b;
  --shadow: 0 22px 60px rgba(17, 24, 32, .12);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  color: var(--ink);
  font-family: Arial, Helvetica, sans-serif;
  line-height: 1.68;
  background:
    linear-gradient(90deg, rgba(17, 24, 32, .05) 1px, transparent 1px),
    linear-gradient(180deg, #fafafa, #edf1f3);
  background-size: 42px 42px, auto;
}

a { color: var(--water); text-underline-offset: 3px; }
img { max-width: 100%; height: auto; display: block; }

.topbar {
  padding: 9px clamp(18px, 5vw, 72px);
  color: rgba(255,255,255,.78);
  background: #0c1218;
  font-size: 13px;
}

.site-nav {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 22px;
  padding: 15px clamp(18px, 5vw, 72px);
  background: rgba(255,255,255,.96);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(12px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  color: var(--ink);
  font-weight: 900;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 42px;
  height: 42px;
  place-items: center;
  color: #fff;
  background: linear-gradient(135deg, var(--steel), var(--water));
  border-radius: 3px;
}

.nav-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 8px 16px;
  font-size: 14px;
}

.nav-links a {
  color: var(--ink);
  font-weight: 700;
  text-decoration: none;
}

.nav-links a:hover,
.nav-links a[aria-current="page"] { color: var(--oxide); }

.hero {
  position: relative;
  display: grid;
  min-height: 620px;
  grid-template-columns: minmax(0, 1.05fr) minmax(340px, .95fr);
  align-items: stretch;
  background: var(--steel);
  color: #fff;
  overflow: hidden;
}

.hero-copy {
  z-index: 2;
  padding: clamp(54px, 8vw, 104px) clamp(18px, 5vw, 72px);
}

.eyebrow {
  display: inline-block;
  color: var(--safety);
  font-size: 12px;
  font-weight: 900;
  letter-spacing: .12em;
  text-transform: uppercase;
}

.hero h1 {
  max-width: 850px;
  margin: 16px 0 20px;
  font-size: clamp(42px, 6vw, 78px);
  line-height: 1.01;
}

.hero p {
  max-width: 720px;
  color: rgba(255,255,255,.82);
  font-size: 19px;
}

.hero-media {
  min-height: 420px;
  background:
    linear-gradient(90deg, rgba(29,42,54,.96), rgba(29,42,54,.08) 38%, rgba(29,42,54,.08)),
    url("/assets/images/sedimentation-treatment-hero.png") center/cover;
}

.hero-actions,
.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.button {
  display: inline-flex;
  min-height: 46px;
  align-items: center;
  justify-content: center;
  padding: 0 18px;
  border-radius: 3px;
  background: var(--safety);
  color: #111820;
  font-weight: 900;
  text-decoration: none;
}

.button.secondary {
  color: #fff;
  background: transparent;
  border: 1px solid rgba(255,255,255,.45);
}

.metrics {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: var(--line);
  margin: 0 clamp(18px, 5vw, 72px);
  transform: translateY(-36px);
  box-shadow: var(--shadow);
}

.metric {
  padding: 24px;
  background: var(--paper);
}

.metric strong {
  display: block;
  color: var(--steel);
  font-size: 28px;
}

.metric span { color: var(--muted); }

.shell {
  width: min(1180px, calc(100% - 36px));
  margin: 0 auto 76px;
}

.section {
  margin: 36px 0;
  padding: clamp(26px, 4vw, 46px);
  background: var(--paper);
  border-top: 6px solid var(--steel);
  box-shadow: 0 16px 42px rgba(17, 24, 32, .08);
}

.section h2,
.page-card h1,
.page-card h2 { color: var(--steel); }

.section h2 {
  margin-top: 0;
  font-size: clamp(28px, 4vw, 44px);
  line-height: 1.1;
}

.lead {
  max-width: 900px;
  color: var(--muted);
  font-size: 19px;
}

.grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
  margin: 28px 0;
}

.card,
.article-card {
  padding: 22px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-left: 5px solid var(--water);
}

.article-card {
  display: flex;
  min-height: 230px;
  flex-direction: column;
  justify-content: space-between;
  color: var(--ink);
  text-decoration: none;
  transition: transform .18s ease, box-shadow .18s ease;
}

.article-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 18px 36px rgba(17, 24, 32, .12);
}

.card h3,
.article-card strong {
  margin-top: 0;
  color: var(--steel);
  font-size: 20px;
  line-height: 1.25;
}

.split {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 300px;
  gap: 28px;
  align-items: start;
}

.page-shell {
  width: min(1160px, calc(100% - 36px));
  margin: 38px auto 76px;
}

.page-card {
  padding: clamp(28px, 4vw, 48px);
  background: var(--paper);
  border-top: 6px solid var(--steel);
  box-shadow: var(--shadow);
}

.page-card h1 {
  margin: 8px 0 18px;
  font-size: clamp(36px, 5vw, 58px);
  line-height: 1.05;
}

.toc {
  position: sticky;
  top: 88px;
  padding: 20px;
  background: #101820;
  color: #fff;
}

.toc strong { display: block; margin-bottom: 12px; color: var(--safety); }
.toc a { display: block; margin: 10px 0; color: #fff; text-decoration: none; }

.article-image {
  margin: 28px 0;
  border: 1px solid var(--line);
  box-shadow: 0 18px 42px rgba(17, 24, 32, .12);
}

.caption {
  margin: 10px 0 0;
  padding-left: 14px;
  color: var(--muted);
  border-left: 4px solid var(--safety);
  font-style: italic;
}

.site-footer {
  display: flex;
  justify-content: space-between;
  gap: 22px;
  padding: 34px clamp(18px, 5vw, 72px);
  color: rgba(255,255,255,.76);
  background: #0c1218;
}

.site-footer a { color: #fff; }
.footer-links { display: flex; flex-wrap: wrap; gap: 14px; }

#xq-floating-contact {
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 99999;
  width: 320px;
  background: #fff;
  border-radius: 12px;
  box-shadow: 0 10px 30px rgba(0,0,0,.2);
  overflow: hidden;
  font-family: "Microsoft YaHei", Arial, sans-serif;
  display: block;
}
#xq-floating-contact .header {
  background: linear-gradient(90deg, #0078d4, #00b0f0);
  color: #fff;
  padding: 15px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
#xq-floating-contact .header h3 { margin: 0; font-size: 17px; font-weight: 600; }
#xq-floating-contact .close { font-size: 26px; line-height: 1; opacity: .9; cursor: pointer; }
#xq-floating-contact .body { padding: 18px; line-height: 1.6; color: #333; }
#xq-floating-contact .body a,
#xq-floating-contact .email-text {
  display: block;
  padding: 10px 0;
  color: #0078d4;
  text-decoration: none;
  border-bottom: 1px solid #eee;
}
#xq-floating-contact .body .main-site {
  background: #0078d4;
  color: #fff;
  text-align: center;
  border-radius: 6px;
  margin-top: 15px;
  padding: 12px;
  font-weight: bold;
}
#xq-floating-contact .close-btn {
  display: block;
  width: 100%;
  text-align: center;
  padding: 10px;
  background: #f1f1f1;
  color: #333;
  border-radius: 6px;
  margin-top: 15px;
  font-weight: 600;
  cursor: pointer;
}

@media (max-width: 920px) {
  .site-nav,
  .site-footer { align-items: flex-start; flex-direction: column; }
  .hero,
  .metrics,
  .grid,
  .split { grid-template-columns: 1fr; }
  .hero { min-height: auto; }
  .hero-media { min-height: 300px; }
  .metrics { transform: none; margin-top: 18px; }
  .toc { position: static; }
}

@media (max-width: 520px) {
  #xq-floating-contact {
    right: 12px;
    bottom: 12px;
    width: min(320px, calc(100% - 24px));
  }
}