* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: -apple-system, BlinkMacSystemFont, sans-serif; background: #f5f5f5; }

/* 移动端响应式头部 */
header { background: linear-gradient(135deg, #667eea, #764ba2); color: white; padding: 1rem; }
header nav { max-width: 1200px; margin: 0 auto; display: flex; flex-direction: column; gap: 0.5rem; }
header h1 { font-size: 1.5rem; text-align: center; }
header ul { 
  list-style: none; 
  display: flex; 
  flex-wrap: wrap; 
  justify-content: center; 
  gap: 0.75rem; 
  padding: 0.5rem 0;
}
header a { color: white; text-decoration: none; font-size: 0.95rem; }

/* 平板及以上 */
@media (min-width: 768px) {
  header { padding: 1rem 2rem; }
  header nav { flex-direction: row; justify-content: space-between; align-items: center; }
  header ul { gap: 2rem; padding: 0; }
  header a { font-size: 1rem; }
}

/* 移动端主内容 */
main { max-width: 1200px; margin: 0 auto; padding: 1rem; }
.hero { text-align: center; padding: 2rem 1rem; background: white; border-radius: 12px; margin-bottom: 1.5rem; }
.hero h2 { font-size: 1.5rem; margin-bottom: 0.5rem; }
.hero p { font-size: 1rem; color: #666; }

@media (min-width: 768px) {
  main { padding: 2rem; }
  .hero { padding: 4rem 2rem; margin-bottom: 2rem; }
  .hero h2 { font-size: 2rem; }
  .hero p { font-size: 1.2rem; }
}

/* 功能卡片网格 */
.features { display: grid; grid-template-columns: 1fr; gap: 1rem; }

@media (min-width: 480px) {
  .features { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 1.5rem; }
}

@media (min-width: 768px) {
  .features { gap: 2rem; }
}

/* 卡片样式 */
.feature-card { 
  background: white; 
  padding: 1.5rem; 
  border-radius: 12px; 
  text-align: center; 
}
.feature-card h3 { font-size: 1.2rem; margin-bottom: 0.5rem; }
.feature-card p { font-size: 0.9rem; color: #666; margin-bottom: 1rem; }

@media (min-width: 768px) {
  .feature-card { padding: 2rem; }
  .feature-card h3 { font-size: 1.5rem; }
  .feature-card p { font-size: 1rem; }
}

/* 按钮触控优化 */
.btn { 
  display: inline-block; 
  padding: 0.75rem 1.5rem; 
  background: linear-gradient(135deg, #667eea, #764ba2); 
  color: white; 
  text-decoration: none; 
  border-radius: 8px; 
  font-size: 1rem;
  min-height: 44px;
  line-height: 1.5;
}

@media (min-width: 768px) {
  .btn { padding: 0.75rem 1.5rem; }
}

/* 底部 */
footer { text-align: center; padding: 1.5rem; color: #666; font-size: 0.85rem; }
@media (min-width: 768px) {
  footer { padding: 2rem; font-size: 1rem; }
}