:root {
  --bg-main: #090d16;
  --bg-card: #111726;
  --bg-card-hover: #162035;
  --bg-glass: rgba(17, 23, 38, 0.75);
  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-active: rgba(59, 130, 246, 0.35);
  
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-tertiary: #64748b;
  
  --accent-blue: #3b82f6;
  --accent-blue-glow: rgba(59, 130, 246, 0.25);
  --accent-cyan: #38bdf8;
  --accent-emerald: #10b981;
  --accent-amber: #f59e0b;
  
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "JetBrains Mono", monospace;
  
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;
  
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.25);
  --shadow-md: 0 10px 30px -10px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 50px -10px rgba(59, 130, 246, 0.2);
}

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

html {
  font-family: var(--font-sans);
  background-color: var(--bg-main);
  color: var(--text-primary);
  line-height: 1.6;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
  background: radial-gradient(circle at 50% -20%, rgba(37, 99, 235, 0.15), transparent 70%),
              radial-gradient(circle at 100% 40%, rgba(56, 189, 248, 0.06), transparent 50%),
              var(--bg-main);
}

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

/* 顶部导航 */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  background-color: rgba(9, 13, 22, 0.8);
  border-bottom: 1px solid var(--border-subtle);
  transition: border-color 0.2s ease;
}

.nav-container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand-link {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.brand-logo {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  display: block;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.75rem;
  font-size: 0.92rem;
  color: var(--text-secondary);
}

.nav-link:hover {
  color: var(--text-primary);
}

.nav-cta {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.45rem 1rem;
  background-color: rgba(255, 255, 255, 0.06);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  color: var(--text-primary);
  font-weight: 500;
  transition: all 0.2s ease;
}

.nav-cta:hover {
  background-color: rgba(255, 255, 255, 0.12);
  border-color: rgba(255, 255, 255, 0.2);
}

/* 主内容布局 */
main {
  flex: 1;
}

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Hero 区域 */
.hero {
  padding: 5.5rem 0 4rem;
  text-align: center;
  position: relative;
}

.hero-badge-wrap {
  display: inline-flex;
  margin-bottom: 1.75rem;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.35rem 0.9rem;
  background: rgba(59, 130, 246, 0.1);
  border: 1px solid rgba(59, 130, 246, 0.25);
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  color: var(--accent-cyan);
  letter-spacing: 0.02em;
}

.hero-badge-dot {
  width: 6px;
  height: 6px;
  background-color: var(--accent-cyan);
  border-radius: 50%;
  box-shadow: 0 0 8px var(--accent-cyan);
}

.hero-icon-container {
  margin: 0 auto 2rem;
  width: 120px;
  height: 120px;
  position: relative;
}

.hero-app-icon {
  width: 100%;
  height: 100%;
  border-radius: 26px;
  box-shadow: 0 16px 40px -10px rgba(0, 0, 0, 0.6),
              0 0 40px -10px rgba(59, 130, 246, 0.4);
  display: block;
}

.hero-title {
  font-size: clamp(2.5rem, 5vw, 3.8rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: 1.25rem;
  background: linear-gradient(180deg, #ffffff 30%, #cbd5e1 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-size: clamp(1.1rem, 2.2vw, 1.35rem);
  color: var(--text-secondary);
  max-width: 680px;
  margin: 0 auto 2.5rem;
  font-weight: 400;
  line-height: 1.6;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  margin-bottom: 2.5rem;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.85rem 1.8rem;
  background: linear-gradient(135deg, #2563eb, #1d4ed8);
  color: #ffffff;
  font-weight: 600;
  border-radius: var(--radius-md);
  box-shadow: 0 10px 25px -6px rgba(37, 99, 235, 0.5);
  transition: all 0.2s ease;
  border: 1px solid rgba(255, 255, 255, 0.15);
}

.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 14px 30px -6px rgba(37, 99, 235, 0.6);
  background: linear-gradient(135deg, #3b82f6, #1d4ed8);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.85rem 1.6rem;
  background-color: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  font-weight: 500;
  border-radius: var(--radius-md);
  transition: all 0.2s ease;
}

.btn-secondary:hover {
  background-color: rgba(255, 255, 255, 0.09);
  border-color: rgba(255, 255, 255, 0.2);
}

.hero-meta {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 1.5rem;
  font-size: 0.85rem;
  color: var(--text-tertiary);
}

.hero-meta-item {
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

/* 事实与哲学对比条 */
.strip {
  padding: 1.5rem 0;
  border-top: 1px solid var(--border-subtle);
  border-bottom: 1px solid var(--border-subtle);
  background: rgba(17, 23, 38, 0.4);
}

.strip-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.5rem;
  text-align: center;
}

.strip-item h4 {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.25rem;
}

.strip-item p {
  font-size: 0.82rem;
  color: var(--text-secondary);
}

/* 功能区 (Features) */
.section {
  padding: 6rem 0;
}

.section-header {
  text-align: center;
  max-width: 650px;
  margin: 0 auto 3.5rem;
}

.section-tag {
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent-blue);
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.section-title {
  font-size: 2.1rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 0.75rem;
  color: var(--text-primary);
}

.section-desc {
  font-size: 1.05rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 1.5rem;
}

.feature-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 2.2rem;
  transition: all 0.25s ease;
  display: flex;
  flex-direction: column;
}

.feature-card:hover {
  background-color: var(--bg-card-hover);
  border-color: var(--border-active);
  transform: translateY(-2px);
  box-shadow: var(--shadow-glow);
}

.feature-icon-box {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  background: rgba(59, 130, 246, 0.1);
  border: 1px solid rgba(59, 130, 246, 0.2);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.5rem;
  color: var(--accent-cyan);
}

.feature-icon-box svg {
  width: 24px;
  height: 24px;
}

.feature-title {
  font-size: 1.3rem;
  font-weight: 600;
  margin-bottom: 0.8rem;
  color: var(--text-primary);
}

.feature-desc {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.65;
  margin-bottom: 1.25rem;
  flex: 1;
}

.feature-list {
  list-style: none;
  border-top: 1px solid var(--border-subtle);
  padding-top: 1rem;
  font-size: 0.88rem;
  color: var(--text-secondary);
}

.feature-list li {
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
  margin-bottom: 0.5rem;
}

.feature-list li::before {
  content: "•";
  color: var(--accent-blue);
  font-weight: bold;
}

/* 架构与安全模块 (Architecture & Privacy) */
.arch-card {
  background: linear-gradient(180deg, #111726, #0d121e);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 3rem;
  margin-bottom: 2rem;
}

.arch-header {
  max-width: 600px;
  margin-bottom: 2.5rem;
}

.flow-diagram {
  background: rgba(0, 0, 0, 0.35);
  border: 1px solid rgba(255, 255, 255, 0.05);
  border-radius: var(--radius-md);
  padding: 2rem 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  margin-bottom: 2rem;
}

@media (min-width: 768px) {
  .flow-diagram {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }
}

.flow-node {
  flex: 1;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  text-align: center;
}

.flow-node.highlight {
  border-color: var(--border-active);
  background: rgba(59, 130, 246, 0.06);
}

.flow-node-title {
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 0.25rem;
  color: var(--text-primary);
}

.flow-node-desc {
  font-size: 0.78rem;
  color: var(--text-tertiary);
}

.flow-arrow {
  color: var(--accent-blue);
  text-align: center;
  font-size: 0.85rem;
  font-weight: 500;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.25rem;
}

.arch-points {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.5rem;
}

.arch-point h4 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.4rem;
  color: var(--text-primary);
}

.arch-point p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.55;
}

/* 开发者自白 / 关于我们 (Manifesto) */
.manifesto-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 2.5rem;
  position: relative;
  overflow: hidden;
}

.manifesto-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: var(--accent-blue);
}

.manifesto-text {
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.8;
  margin-bottom: 1rem;
}

.manifesto-text:last-of-type {
  margin-bottom: 1.5rem;
}

.manifesto-author {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 0.92rem;
  color: var(--text-primary);
}

.manifesto-tag {
  font-size: 0.8rem;
  color: var(--text-tertiary);
}

/* FAQ 常见问答 */
.faq-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 1.5rem;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 1.5rem;
}

.faq-question {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.6rem;
}

.faq-answer {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* 页脚 */
.footer {
  border-top: 1px solid var(--border-subtle);
  background-color: #070a11;
  padding: 4rem 0 2rem;
  margin-top: 4rem;
  font-size: 0.88rem;
  color: var(--text-tertiary);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr repeat(auto-fit, minmax(140px, 1fr));
  gap: 2.5rem;
  margin-bottom: 3rem;
}

.footer-brand h3 {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.footer-brand p {
  max-width: 340px;
  line-height: 1.6;
}

.footer-col h5 {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 1rem;
}

.footer-col ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.footer-col a:hover {
  color: var(--text-primary);
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  padding-top: 1.75rem;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  font-size: 0.82rem;
}

/* 法律文档专用排版 (Legal pages: privacy, terms) */
.legal-page {
  padding: 4rem 0 6rem;
  max-width: 820px;
  margin: 0 auto;
}

.legal-header {
  border-bottom: 1px solid var(--border-subtle);
  padding-bottom: 2rem;
  margin-bottom: 2.5rem;
}

.legal-header h1 {
  font-size: 2.4rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
}

.legal-date {
  font-size: 0.9rem;
  color: var(--text-tertiary);
}

.legal-content h2 {
  font-size: 1.4rem;
  font-weight: 600;
  margin: 2.2rem 0 1rem;
  color: var(--text-primary);
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
  padding-bottom: 0.5rem;
}

.legal-content h3 {
  font-size: 1.15rem;
  font-weight: 600;
  margin: 1.5rem 0 0.75rem;
  color: var(--text-primary);
}

.legal-content p {
  margin-bottom: 1rem;
  color: var(--text-secondary);
  line-height: 1.75;
}

.legal-content ul, .legal-content ol {
  margin: 0 0 1.25rem 1.5rem;
  color: var(--text-secondary);
  line-height: 1.75;
}

.legal-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0 2rem;
  font-size: 0.88rem;
}

.legal-content th, .legal-content td {
  border: 1px solid var(--border-subtle);
  padding: 0.75rem 1rem;
  text-align: left;
}

.legal-content th {
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-primary);
}

.legal-content strong {
  color: var(--text-primary);
}

/* 响应式调整 */
@media (max-width: 640px) {
  .hero {
    padding: 3.5rem 0 2.5rem;
  }
  .nav-links {
    display: none;
  }
  .features-grid {
    grid-template-columns: 1fr;
  }
  .arch-card {
    padding: 1.5rem;
  }
}