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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  color: #1a1a2e;
  background: #fafafa;
  line-height: 1.6;
}

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

/* Nav */
.nav {
  background: rgba(255,255,255,0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid #eee;
  position: sticky;
  top: 0;
  z-index: 100;
}
.nav-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.logo {
  font-size: 1.4rem;
  font-weight: 700;
  color: #1a1a2e;
  letter-spacing: -0.5px;
}
.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
}
.nav-links a { font-size: 0.95rem; color: #555; }
.nav-links a:hover { color: #1a1a2e; }
.btn-chat {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: #fff !important;
  padding: 8px 20px;
  border-radius: 20px;
  font-size: 0.9rem;
  font-weight: 500;
  transition: transform 0.15s;
}
.btn-chat:hover { transform: scale(1.05); }

/* Hero */
.hero {
  max-width: 1100px;
  margin: 0 auto;
  padding: 80px 24px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
}
.hero-content h1 {
  font-size: 3rem;
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: -1px;
}
.hero-sub {
  margin-top: 20px;
  font-size: 1.1rem;
  color: #555;
  line-height: 1.8;
}
.hero-actions {
  margin-top: 32px;
  display: flex;
  gap: 16px;
}
.btn-primary {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: #fff;
  padding: 14px 36px;
  border-radius: 28px;
  font-size: 1rem;
  font-weight: 600;
  transition: transform 0.15s, box-shadow 0.15s;
  box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 6px 20px rgba(102, 126, 234, 0.5); }
.btn-secondary {
  border: 2px solid #ddd;
  padding: 14px 36px;
  border-radius: 28px;
  font-size: 1rem;
  font-weight: 500;
  color: #555;
  transition: border-color 0.15s;
}
.btn-secondary:hover { border-color: #667eea; color: #667eea; }

/* Chat preview */
.chat-preview {
  background: #fff;
  border-radius: 16px;
  box-shadow: 0 8px 40px rgba(0,0,0,0.08);
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}
.chat-bubble {
  max-width: 85%;
  padding: 12px 16px;
  border-radius: 12px;
  font-size: 0.9rem;
  line-height: 1.6;
}
.chat-bubble.user {
  align-self: flex-end;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: #fff;
  border-bottom-right-radius: 4px;
}
.chat-bubble.ai {
  align-self: flex-start;
  background: #f4f4f8;
  color: #333;
  border-bottom-left-radius: 4px;
}

/* Features */
.features {
  background: #fff;
  padding: 80px 24px;
}
.features h2, .about h2 {
  text-align: center;
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 48px;
}
.feature-grid {
  max-width: 1000px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 32px;
}
.feature-card {
  padding: 32px 24px;
  border-radius: 12px;
  border: 1px solid #eee;
  transition: box-shadow 0.2s;
}
.feature-card:hover { box-shadow: 0 4px 20px rgba(0,0,0,0.06); }
.feature-icon { font-size: 2rem; margin-bottom: 12px; }
.feature-card h3 { font-size: 1.1rem; font-weight: 600; margin-bottom: 8px; }
.feature-card p { font-size: 0.9rem; color: #666; line-height: 1.7; }

/* About */
.about {
  max-width: 700px;
  margin: 0 auto;
  padding: 80px 24px;
  text-align: center;
}
.about p { font-size: 1.05rem; color: #555; line-height: 1.8; margin-bottom: 16px; }
.about a { color: #667eea; font-weight: 600; }
.about a:hover { text-decoration: underline; }
.about-cta { margin-top: 24px; }

/* Footer */
.footer {
  border-top: 1px solid #eee;
  padding: 32px 24px;
  text-align: center;
  color: #999;
  font-size: 0.9rem;
}
.footer-links { margin-top: 8px; display: flex; gap: 20px; justify-content: center; }
.footer-links a:hover { color: #667eea; }

.footer-icp {
  margin-top: 16px;
  font-size: 0.82rem;
  color: #bbb;
  display: flex;
  gap: 16px;
  justify-content: center;
}
.footer-icp a { color: #bbb; }
.footer-icp a:hover { color: #667eea; }

@media (max-width: 768px) {
  .hero {
    grid-template-columns: 1fr;
    padding: 48px 24px;
    gap: 40px;
  }
  .hero-content h1 { font-size: 2.2rem; }
  .hero-actions { flex-direction: column; }
  .nav-links { gap: 16px; }
  .nav-links a:not(.btn-chat) { display: none; }
}