/* 溯达官网 - 深色调高级感（类 Linear / Vercel / Anthropic 风格）*/
:root {
  --brand: #818cf8;
  --brand-mid: #6366f1;
  --brand-dark: #4f46e5;
  --brand-glow: rgba(129, 140, 248, 0.4);

  --bg: #050811;
  --bg-card: #0d1224;
  --bg-section: #080c18;
  --bg-elevated: #11172b;

  --text: #f8fafc;
  --text-muted: #94a3b8;
  --text-dim: #64748b;

  --border: rgba(255, 255, 255, 0.08);
  --border-strong: rgba(255, 255, 255, 0.14);
  --border-glow: rgba(129, 140, 248, 0.3);

  --shadow-glow: 0 20px 60px rgba(99, 102, 241, 0.25);
  --shadow-card: 0 1px 0 rgba(255, 255, 255, 0.05) inset, 0 12px 32px rgba(0, 0, 0, 0.5);

  --radius: 12px;
  --radius-lg: 18px;
  --max-w: 1200px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html {
  scroll-behavior: smooth;
  background: var(--bg);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Inter", "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: var(--bg);
  background-image:
    radial-gradient(circle at 20% 0%, rgba(99, 102, 241, 0.12) 0%, transparent 40%),
    radial-gradient(circle at 80% 100%, rgba(168, 85, 247, 0.08) 0%, transparent 40%);
  background-attachment: fixed;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a { color: inherit; text-decoration: none; }
img, svg { max-width: 100%; display: block; }

/* ===== 顶部导航 ===== */
.nav {
  position: sticky;
  top: 0;
  background: rgba(5, 8, 17, 0.7);
  backdrop-filter: blur(24px) saturate(180%);
  border-bottom: 1px solid var(--border);
  z-index: 100;
}
.nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  align-items: center;
  gap: 36px;
}
.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 17px;
  color: var(--text);
  letter-spacing: -0.3px;
}
.nav-logo-mark {
  width: 30px;
  height: 30px;
  background: linear-gradient(135deg, var(--brand), var(--brand-dark));
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 800;
  font-size: 15px;
  box-shadow: 0 4px 12px var(--brand-glow);
}
.nav-links {
  display: flex;
  gap: 28px;
  list-style: none;
  margin-left: 12px;
}
.nav-links a {
  font-size: 14px;
  color: var(--text-muted);
  font-weight: 500;
  transition: color 0.2s;
}
.nav-links a:hover { color: var(--text); }
.nav-cta {
  margin-left: auto;
  display: flex;
  gap: 10px;
  align-items: center;
}

/* ===== 按钮 ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 11px 22px;
  border-radius: 10px;
  font-size: 14px;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.2s ease-out;
  white-space: nowrap;
  letter-spacing: 0.1px;
}
.btn-primary {
  background: linear-gradient(135deg, var(--brand) 0%, var(--brand-dark) 100%);
  color: #fff;
  box-shadow: 0 1px 0 rgba(255,255,255,0.15) inset, 0 8px 24px rgba(99, 102, 241, 0.35);
}
.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 1px 0 rgba(255,255,255,0.2) inset, 0 12px 32px rgba(99, 102, 241, 0.5);
}
.btn-ghost {
  background: rgba(255, 255, 255, 0.04);
  color: var(--text);
  border: 1px solid var(--border-strong);
}
.btn-ghost:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: var(--brand);
}
.btn-large { padding: 14px 30px; font-size: 15px; }

/* ===== 通用容器 ===== */
.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

.section { padding: 100px 0; }

.section-title {
  font-size: 36px;
  font-weight: 700;
  text-align: center;
  margin-bottom: 16px;
  color: var(--text);
  letter-spacing: -0.5px;
  background: linear-gradient(180deg, #fff 0%, #cbd5e1 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.section-subtitle {
  text-align: center;
  font-size: 16px;
  color: var(--text-muted);
  margin: 0 auto 64px;
  max-width: 640px;
  line-height: 1.7;
}

/* ===== Hero ===== */
.hero {
  position: relative;
  padding: 120px 24px 100px;
  text-align: center;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  top: 0; left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 600px;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.25) 0%, transparent 60%);
  pointer-events: none;
  z-index: -1;
}
.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 14px;
  background: rgba(129, 140, 248, 0.12);
  color: var(--brand);
  border: 1px solid rgba(129, 140, 248, 0.25);
  border-radius: 100px;
  font-size: 13px;
  font-weight: 500;
  margin-bottom: 28px;
  backdrop-filter: blur(8px);
}
.hero-eyebrow::before {
  content: '';
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--brand);
  box-shadow: 0 0 8px var(--brand);
}
.hero-title {
  font-size: 56px;
  font-weight: 800;
  line-height: 1.1;
  max-width: 880px;
  margin: 0 auto 24px;
  color: var(--text);
  letter-spacing: -1.5px;
  background: linear-gradient(180deg, #fff 0%, #94a3b8 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-title .accent {
  background: linear-gradient(135deg, var(--brand) 0%, #c084fc 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-subtitle {
  font-size: 18px;
  color: var(--text-muted);
  max-width: 640px;
  margin: 0 auto 40px;
  line-height: 1.7;
}
.hero-cta {
  display: flex;
  justify-content: center;
  gap: 14px;
  flex-wrap: wrap;
}
.hero-trust {
  margin-top: 56px;
  font-size: 13px;
  color: var(--text-dim);
  letter-spacing: 0.2px;
}

/* ===== Feature 卡片网格 ===== */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
}
.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: all 0.25s ease-out;
  position: relative;
  overflow: hidden;
}
.feature-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 100%;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--border-glow), transparent);
  opacity: 0;
  transition: opacity 0.25s;
}
.feature-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-strong);
  background: var(--bg-elevated);
}
.feature-card:hover::before { opacity: 1; }
.feature-icon {
  width: 44px;
  height: 44px;
  border-radius: 10px;
  background: linear-gradient(135deg, rgba(129, 140, 248, 0.2), rgba(99, 102, 241, 0.1));
  border: 1px solid rgba(129, 140, 248, 0.3);
  color: var(--brand);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  margin-bottom: 20px;
}
.feature-title {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--text);
  letter-spacing: -0.2px;
}
.feature-desc {
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.7;
}

/* ===== 详细功能行（双列）===== */
.detail-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 80px;
  align-items: center;
  margin-bottom: 120px;
}
.detail-row.reverse .detail-text { order: 2; }
.detail-row.reverse .detail-visual { order: 1; }
.detail-eyebrow {
  display: inline-block;
  padding: 5px 12px;
  background: rgba(129, 140, 248, 0.12);
  color: var(--brand);
  border: 1px solid rgba(129, 140, 248, 0.25);
  border-radius: 100px;
  font-size: 12px;
  font-weight: 600;
  margin-bottom: 20px;
  letter-spacing: 0.3px;
}
.detail-title {
  font-size: 32px;
  font-weight: 700;
  line-height: 1.25;
  margin-bottom: 20px;
  letter-spacing: -0.5px;
  color: var(--text);
}
.detail-desc {
  font-size: 15px;
  color: var(--text-muted);
  line-height: 1.8;
  margin-bottom: 28px;
}
.detail-list {
  list-style: none;
  margin-bottom: 28px;
}
.detail-list li {
  padding: 8px 0 8px 28px;
  position: relative;
  font-size: 14px;
  color: var(--text-muted);
}
.detail-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 14px;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: rgba(129, 140, 248, 0.15);
  border: 1px solid var(--brand);
}
.detail-list li::after {
  content: "✓";
  position: absolute;
  left: 3px;
  top: 8px;
  color: var(--brand);
  font-size: 9px;
  font-weight: 700;
}
.detail-visual {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 48px 32px;
  min-height: 360px;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
}
.detail-visual::before {
  content: '';
  position: absolute;
  top: -50%; left: -50%;
  width: 200%; height: 200%;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.08) 0%, transparent 50%);
  pointer-events: none;
}
.detail-visual .mock-screen {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px;
  box-shadow: var(--shadow-card);
  width: 100%;
  max-width: 360px;
  position: relative;
  z-index: 1;
}

/* ===== 套餐价格 ===== */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
  max-width: 1000px;
  margin: 0 auto;
}
.pricing-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 36px 30px;
  position: relative;
  transition: all 0.25s;
}
.pricing-card:hover {
  border-color: var(--border-strong);
  transform: translateY(-2px);
}
.pricing-card.featured {
  border: 1px solid var(--brand);
  background: linear-gradient(180deg, var(--bg-card) 0%, var(--bg-elevated) 100%);
  box-shadow: 0 0 0 1px rgba(129, 140, 248, 0.3), 0 24px 60px rgba(99, 102, 241, 0.2);
  transform: translateY(-6px);
}
.pricing-card .featured-tag {
  position: absolute;
  top: -12px;
  left: 50%;
  transform: translateX(-50%);
  background: linear-gradient(135deg, var(--brand), var(--brand-dark));
  color: #fff;
  padding: 5px 16px;
  border-radius: 100px;
  font-size: 12px;
  font-weight: 600;
  box-shadow: 0 4px 12px var(--brand-glow);
}
.pricing-name {
  font-size: 13px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.8px;
  margin-bottom: 12px;
  font-weight: 600;
}
.pricing-price {
  font-size: 42px;
  font-weight: 800;
  color: var(--text);
  margin-bottom: 4px;
  letter-spacing: -1px;
}
.pricing-price small {
  font-size: 14px;
  font-weight: 500;
  color: var(--text-muted);
}
.pricing-desc {
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 28px;
  padding-bottom: 28px;
  border-bottom: 1px solid var(--border);
}
.pricing-list {
  list-style: none;
  margin-bottom: 32px;
}
.pricing-list li {
  padding: 8px 0 8px 24px;
  position: relative;
  font-size: 14px;
  color: var(--text-muted);
}
.pricing-list li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: var(--brand);
  font-weight: 700;
}

/* ===== Footer ===== */
.footer {
  background: var(--bg-section);
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  padding: 72px 0 32px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 48px;
  margin-bottom: 48px;
}
.footer-brand {
  font-size: 17px;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 10px;
}
.footer-tagline {
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.8;
  max-width: 360px;
}
.footer-section h4 {
  color: var(--text);
  font-size: 13px;
  margin-bottom: 18px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}
.footer-section ul { list-style: none; }
.footer-section li { margin-bottom: 10px; }
.footer-section a {
  color: var(--text-muted);
  font-size: 14px;
  transition: color 0.2s;
}
.footer-section a:hover { color: var(--text); }
.footer-bottom {
  border-top: 1px solid var(--border);
  padding-top: 28px;
  text-align: center;
  font-size: 12px;
  color: var(--text-dim);
}

/* ===== 长文页面（隐私 / 条款）===== */
.doc-page {
  max-width: 820px;
  margin: 80px auto;
  padding: 0 24px;
}
.doc-page h1 {
  font-size: 40px;
  font-weight: 800;
  margin-bottom: 12px;
  color: var(--text);
  letter-spacing: -0.8px;
  background: linear-gradient(180deg, #fff 0%, #cbd5e1 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.doc-page .doc-meta {
  font-size: 13px;
  color: var(--text-dim);
  margin-bottom: 56px;
  padding-bottom: 28px;
  border-bottom: 1px solid var(--border);
}
.doc-page h2 {
  font-size: 24px;
  font-weight: 700;
  margin-top: 48px;
  margin-bottom: 18px;
  color: var(--text);
  letter-spacing: -0.3px;
}
.doc-page h3 {
  font-size: 18px;
  font-weight: 600;
  margin-top: 28px;
  margin-bottom: 12px;
  color: var(--text);
}
.doc-page p {
  font-size: 15px;
  color: var(--text-muted);
  line-height: 1.85;
  margin-bottom: 18px;
}
.doc-page ul, .doc-page ol {
  margin: 18px 0 18px 28px;
  color: var(--text-muted);
  font-size: 15px;
  line-height: 1.85;
}
.doc-page li { margin-bottom: 10px; }
.doc-page a { color: var(--brand); border-bottom: 1px solid rgba(129, 140, 248, 0.3); }
.doc-page a:hover { border-color: var(--brand); }

/* ===== CTA 大区块 ===== */
.cta-section {
  padding: 100px 24px;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.cta-section::before {
  content: '';
  position: absolute;
  top: 50%; left: 50%;
  transform: translate(-50%, -50%);
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.18) 0%, transparent 60%);
  pointer-events: none;
}
.cta-title {
  font-size: 38px;
  font-weight: 800;
  margin-bottom: 18px;
  color: var(--text);
  letter-spacing: -0.8px;
  background: linear-gradient(180deg, #fff 0%, #cbd5e1 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  position: relative;
  z-index: 1;
}
.cta-desc {
  font-size: 17px;
  color: var(--text-muted);
  max-width: 580px;
  margin: 0 auto 36px;
  position: relative;
  z-index: 1;
}
.cta-section .hero-cta { position: relative; z-index: 1; }

/* ===== 响应式 ===== */
@media (max-width: 900px) {
  .nav-links { display: none; }
  .hero-title { font-size: 36px; }
  .hero-subtitle { font-size: 15px; }
  .section-title { font-size: 28px; }
  .detail-row {
    grid-template-columns: 1fr;
    gap: 36px;
    margin-bottom: 72px;
  }
  .detail-row.reverse .detail-text { order: 1; }
  .detail-row.reverse .detail-visual { order: 2; }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
  .section { padding: 64px 0; }
}

@media (max-width: 600px) {
  .hero { padding: 60px 20px; }
  .hero-title { font-size: 28px; }
  .footer-grid { grid-template-columns: 1fr; }
  .nav-inner { gap: 16px; padding: 12px 16px; }
}