:root {
  --bg: #0b1120;
  --bg-soft: #111827;
  --card: rgba(17, 24, 39, 0.85);
  --text: #e2e8f0;
  --muted: #94a3b8;
  --primary: #38bdf8;
  --primary-strong: #0ea5e9;
  --accent: #06b6d4;
  --accent-strong: #0891b2;
  --border: rgba(148, 163, 184, 0.2);
  --shadow: 0 18px 40px rgba(2, 6, 23, 0.4);
  --radius: 18px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "Segoe UI", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  overflow-x: hidden;
}

a { color: inherit; text-decoration: none; }

.container {
  width: min(1400px, 100%);
  margin: 0 auto;
  padding: 0 3vw;
}

/* ── Background ── */
.bg-glow {
  position: fixed;
  width: 420px;
  height: 420px;
  border-radius: 50%;
  filter: blur(100px);
  opacity: 0.6;
  z-index: -3;
}

.glow-a {
  top: -120px;
  left: -80px;
  background: radial-gradient(circle, rgba(6, 182, 212, 0.4), transparent 70%);
}

.glow-b {
  bottom: -150px;
  right: -100px;
  background: radial-gradient(circle, rgba(56, 189, 248, 0.35), transparent 70%);
}

.bg-grid {
  position: fixed;
  inset: 0;
  background-image: radial-gradient(rgba(148, 163, 184, 0.16) 1px, transparent 1px);
  background-size: 24px 24px;
  pointer-events: none;
  z-index: -4;
}

/* ── Nav ── */
.hero { padding: 20px 0 64px; }

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 12px 18px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: rgba(15, 23, 42, 0.7);
  backdrop-filter: blur(16px);
  box-shadow: 0 10px 30px rgba(2, 6, 23, 0.4);
}

.brand { display: flex; align-items: center; gap: 12px; }
.brand strong { display: block; }
.brand span { font-size: 0.85rem; color: var(--muted); }

.brand-mark {
  width: 38px;
  height: 38px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  background: linear-gradient(135deg, var(--accent), var(--primary));
  color: #fff;
  font-weight: 700;
}

.nav-links { display: flex; gap: 18px; font-size: 0.95rem; color: var(--muted); }
.nav-links a:hover { color: var(--accent); }

.theme-toggle {
  border: 1px solid var(--border);
  padding: 8px 14px;
  border-radius: 999px;
  background: transparent;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 6px;
  cursor: pointer;
}

/* ── Hero Body ── */
.hero-body {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 28px;
  margin-top: 36px;
  align-items: center;
}

.pill {
  display: inline-flex;
  padding: 6px 14px;
  border-radius: 999px;
  background: rgba(6, 182, 212, 0.15);
  color: var(--accent);
  font-weight: 600;
  font-size: 0.9rem;
}

.hero-text h1 { font-size: clamp(2.3rem, 4vw, 3.4rem); margin: 16px 0 12px; }

.hero-actions { display: flex; gap: 14px; flex-wrap: wrap; margin: 16px 0 22px; }

.btn {
  padding: 12px 20px;
  border-radius: 12px;
  border: 1px solid transparent;
  font-weight: 600;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.btn.primary {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 14px 24px rgba(6, 182, 212, 0.35);
}

.btn.primary:hover { transform: translateY(-2px); }
.btn.ghost { border-color: rgba(6, 182, 212, 0.4); color: var(--accent); }

.hero-metrics {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
}

.metric {
  background: var(--card);
  border-radius: 16px;
  border: 1px solid var(--border);
  padding: 14px 16px;
  text-align: center;
}

.metric-num { font-size: 1.6rem; font-weight: 700; display: block; }
.metric-label { color: var(--muted); font-size: 0.85rem; }

/* ── Hero Panel ── */
.hero-panel {
  background: var(--card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  padding: 22px;
  box-shadow: var(--shadow);
}

.panel-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--muted);
  font-size: 0.95rem;
}

.status {
  background: rgba(34, 197, 94, 0.2);
  color: #22c55e;
  padding: 4px 10px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.8rem;
}

.panel-list {
  list-style: none;
  padding: 0;
  margin: 16px 0;
  display: grid;
  gap: 10px;
  color: var(--text);
}

.panel-list li { display: flex; gap: 8px; }
.panel-list li::before { content: "●"; color: var(--accent); }
.panel-footer { color: var(--muted); font-size: 0.9rem; }

/* ── Sections ── */
/* ── Demo Banner ── */
.demo-banner {
  background: var(--card);
  border: 2px solid rgba(6, 182, 212, 0.4);
  border-radius: var(--radius);
  padding: 28px 32px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 24px;
  box-shadow: var(--shadow), 0 0 40px rgba(6, 182, 212, 0.08);
}

.demo-info h2 { margin: 0 0 8px; font-size: 1.4rem; }
.demo-info > p { margin: 0 0 18px; color: var(--muted); }

.demo-credentials { display: flex; gap: 20px; flex-wrap: wrap; }
.demo-field { display: grid; gap: 4px; }

.demo-label {
  font-size: 0.8rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 1px;
  font-weight: 600;
}

.demo-value {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text);
  background: rgba(6, 182, 212, 0.1);
  padding: 6px 14px;
  border-radius: 10px;
  font-family: "Consolas", "Courier New", monospace;
}

.demo-link { color: var(--accent) !important; text-decoration: none; }
.demo-link:hover { text-decoration: underline; }
.demo-action { flex-shrink: 0; }

.section { margin: 0 auto 60px; }

.section-head {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 20px;
  margin-bottom: 20px;
}

.section-head p { color: var(--muted); margin: 8px 0 0; }

/* ── Intro Grid ── */
.intro-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
}

.intro-card {
  background: var(--card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  padding: 24px;
  display: grid;
  gap: 10px;
  box-shadow: var(--shadow);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.intro-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 24px 48px rgba(2, 6, 23, 0.5);
}

.intro-card h3 { margin: 0; }
.intro-card p { margin: 0; color: var(--muted); font-size: 0.95rem; }
.intro-icon { font-size: 2rem; line-height: 1; }

/* ── Service Grid ── */
.service-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 16px;
}

.service-card {
  background: var(--card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  padding: 24px;
  display: grid;
  gap: 12px;
  box-shadow: var(--shadow);
}

.service-card h3 { margin: 0; }
.service-card ul { margin: 0; padding-left: 18px; color: var(--muted); }

.highlight-card { border-color: rgba(6, 182, 212, 0.4); }

/* ── Flow Grid ── */
.flow-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
}

.flow-card {
  background: var(--card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  padding: 24px;
  display: grid;
  gap: 10px;
  text-align: center;
}

.flow-card h3 { margin: 0; }
.flow-card p { margin: 0; color: var(--muted); font-size: 0.92rem; }

.flow-step {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: rgba(6, 182, 212, 0.15);
  color: var(--accent);
  display: grid;
  place-items: center;
  font-size: 1.3rem;
  font-weight: 800;
  margin: 0 auto;
}

/* ── FAQ Grid ── */
.faq-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 16px;
}

.faq-card {
  background: var(--card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  padding: 24px;
  display: grid;
  gap: 8px;
}

.faq-card h3 { margin: 0; font-size: 1.05rem; color: var(--text); }
.faq-card p { margin: 0; color: var(--muted); font-size: 0.95rem; }

/* ── Tools Grid ── */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
}

.tool-card {
  background: var(--card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  padding: 20px;
  display: grid;
  gap: 8px;
  position: relative;
}

.tool-card h3 { margin: 0; }
.tool-card p { margin: 0; color: var(--muted); font-size: 0.92rem; }

.tool-tag {
  position: absolute;
  top: 14px;
  right: 14px;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 700;
}

.tool-tag.essential {
  background: rgba(6, 182, 212, 0.2);
  color: var(--accent);
}

.tools-tip {
  margin-top: 16px;
  color: var(--muted);
  font-size: 0.92rem;
}

.text-link-inline {
  color: var(--accent);
  font-weight: 600;
}

.text-link-inline:hover { text-decoration: underline; }

/* ── Contact Grid ── */
.contact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 16px;
}

.contact-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  display: grid;
  gap: 10px;
}

.contact-card h3 { margin: 0; }

.qq-number {
  font-size: 2rem;
  font-weight: 800;
  color: var(--accent);
  margin: 0;
  letter-spacing: 2px;
}

.qr-card { display: grid; justify-items: center; gap: 14px; }

.qr-img {
  width: 200px;
  height: 200px;
  border-radius: 14px;
  object-fit: cover;
  border: 2px solid var(--border);
}

.contact-tips {
  margin: 8px 0 0;
  padding-left: 18px;
  color: var(--muted);
  font-size: 0.92rem;
}

.contact-tips li { margin-bottom: 4px; }

/* ── Footer ── */
.footer {
  padding: 28px 0 36px;
  border-top: 1px solid var(--border);
  color: var(--muted);
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

/* ── Light Theme ── */
body.light {
  --bg: #f3f6ff;
  --bg-soft: #ffffff;
  --card: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --primary: #2563eb;
  --primary-strong: #1d4ed8;
  --accent: #0891b2;
  --accent-strong: #0e7490;
  --border: rgba(148, 163, 184, 0.35);
  --shadow: 0 18px 40px rgba(15, 23, 42, 0.12);
}

body.light .nav {
  background: rgba(255, 255, 255, 0.8);
  box-shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
}

body.light .bg-grid {
  background-image: radial-gradient(rgba(15, 23, 42, 0.08) 1px, transparent 1px);
}

body.light .bg-glow { opacity: 0.4; }

/* ── To Top ── */
.to-top {
  position: fixed;
  right: 18px;
  bottom: 18px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: none;
  background: var(--accent);
  color: #fff;
  box-shadow: var(--shadow);
  cursor: pointer;
  display: none;
}

.to-top.show { display: grid; place-items: center; }

/* ── Responsive ── */
@media (max-width: 960px) {
  .nav { flex-wrap: wrap; justify-content: center; }
  .nav-links { width: 100%; justify-content: center; }
  .hero-body { grid-template-columns: 1fr; }
  .section-head { flex-direction: column; align-items: flex-start; }
  .hero-metrics { grid-template-columns: 1fr; }
  .demo-banner { flex-direction: column; align-items: flex-start; }
  .demo-credentials { flex-direction: column; }
}