:root {
  --bg: #ffffff;
  --bg-elev: #fafafa;
  --text: #0a0a0a;
  --text-muted: #595959;
  --accent: #d63d3d;
  --accent-hover: #b53131;
  --border: #e8e8e8;
  --radius: 12px;
  --max-w: 1100px;
  --font-en: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, "Helvetica Neue", Arial, sans-serif;
  --font-cn: "PingFang SC", "Hiragino Sans GB", "Songti SC", "Noto Serif SC", serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0a0a0a;
    --bg-elev: #161616;
    --text: #f5f5f5;
    --text-muted: #a8a8a8;
    --accent: #ff5757;
    --accent-hover: #ff7575;
    --border: #2a2a2a;
  }
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-en);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

/* ---------- Header ---------- */
.site-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 22px 32px;
  max-width: var(--max-w);
  margin: 0 auto;
}

.logo {
  display: flex;
  align-items: baseline;
  gap: 10px;
  font-weight: 600;
}

.logo-en {
  font-size: 22px;
  letter-spacing: -0.01em;
}

.logo-cn {
  font-family: var(--font-cn);
  color: var(--text-muted);
  font-size: 18px;
  font-weight: 500;
}

nav {
  display: flex;
  gap: 28px;
}

nav a {
  color: var(--text-muted);
  font-size: 15px;
  transition: color 0.15s ease;
}

nav a:hover {
  color: var(--text);
}

/* ---------- Main ---------- */
main {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 32px;
}

/* ---------- Hero ---------- */
.hero {
  padding: 88px 0 104px;
  text-align: center;
}

.hero h1 {
  font-size: clamp(40px, 7vw, 72px);
  font-weight: 700;
  letter-spacing: -0.025em;
  line-height: 1.08;
  margin-bottom: 24px;
}

.accent {
  color: var(--accent);
}

.lead {
  font-size: 19px;
  color: var(--text-muted);
  max-width: 640px;
  margin: 0 auto 40px;
  line-height: 1.55;
}

.cta-row {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
  align-items: center;
}

.btn-primary,
.btn-secondary {
  display: inline-flex;
  align-items: center;
  padding: 13px 26px;
  border-radius: 8px;
  font-weight: 500;
  font-size: 15px;
  transition: all 0.15s ease;
}

.btn-primary {
  background: var(--accent);
  color: #ffffff;
  border: 1px solid var(--accent);
  cursor: default;
}

.btn-secondary {
  border: 1px solid var(--border);
  color: var(--text);
  background: transparent;
}

.btn-secondary:hover {
  background: var(--bg-elev);
  border-color: var(--text-muted);
}

/* ---------- Features ---------- */
.features {
  padding: 96px 0;
  border-top: 1px solid var(--border);
}

.features h2 {
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 600;
  letter-spacing: -0.015em;
  margin-bottom: 56px;
  text-align: center;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
}

.feature-grid article {
  padding: 32px 28px;
  background: var(--bg-elev);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  transition: border-color 0.2s ease, transform 0.2s ease;
}

.feature-grid article:hover {
  border-color: var(--text-muted);
  transform: translateY(-2px);
}

.feature-grid .icon {
  font-size: 30px;
  margin-bottom: 18px;
}

.feature-grid h3 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 10px;
  letter-spacing: -0.01em;
}

.feature-grid p {
  color: var(--text-muted);
  font-size: 15px;
  line-height: 1.6;
}

/* ---------- About ---------- */
.about {
  padding: 96px 0;
  border-top: 1px solid var(--border);
  max-width: 720px;
  margin: 0 auto;
  text-align: center;
}

.about h2 {
  font-size: clamp(24px, 3.5vw, 32px);
  font-weight: 600;
  letter-spacing: -0.01em;
  margin-bottom: 20px;
}

.about p {
  color: var(--text-muted);
  font-size: 17px;
  line-height: 1.65;
}

.about strong {
  color: var(--text);
  font-weight: 600;
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 56px 32px 32px;
  margin-top: 40px;
}

.footer-grid {
  max-width: var(--max-w);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 36px;
}

.footer-brand {
  font-weight: 600;
  font-size: 18px;
  margin-bottom: 6px;
  display: flex;
  align-items: baseline;
  gap: 8px;
}

.footer-brand-cn {
  font-family: var(--font-cn);
  color: var(--text-muted);
  font-size: 15px;
  font-weight: 500;
}

.footer-tagline {
  color: var(--text-muted);
  font-size: 14px;
}

.footer-label {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 10px;
}

.site-footer a {
  color: var(--text);
  border-bottom: 1px solid var(--border);
  transition: border-color 0.15s ease;
}

.site-footer a:hover {
  border-color: var(--accent);
}

.site-footer div {
  font-size: 14px;
  line-height: 1.75;
}

[data-placeholder] {
  color: var(--text-muted);
  font-style: italic;
  opacity: 0.75;
}

.footer-legal {
  max-width: var(--max-w);
  margin: 40px auto 0;
  padding-top: 24px;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 13px;
}

/* ---------- Responsive ---------- */
@media (max-width: 720px) {
  .site-header {
    padding: 16px 20px;
    flex-wrap: wrap;
    gap: 12px;
  }

  nav {
    gap: 18px;
    font-size: 14px;
  }

  main {
    padding: 0 20px;
  }

  .hero {
    padding: 56px 0 72px;
  }

  .features,
  .about {
    padding: 64px 0;
  }

  .features h2 {
    margin-bottom: 36px;
  }

  .site-footer {
    padding: 40px 20px 24px;
  }
}