/* 基础排版优化 */
body{
  margin:0;
  font-family:-apple-system,BlinkMacSystemFont,"Helvetica Neue",Arial,"PingFang SC","Microsoft YaHei",sans-serif;
  line-height:1.7;
  color:#333;
  background:#fff;
}
/* 头部 */
header{
  background:#1a1a1a;
  color:#fff;
  padding:12px 24px;
  display:flex;
  justify-content:space-between;
  align-items:center;
}
header nav a{
  color:#fff;
  margin-left:18px;
  text-decoration:none;
  transition:opacity .3s;
}
header nav a:hover{
  opacity:.7;
}
/* 视觉横幅 */
.hero{
  padding:96px 20px;
  text-align:center;
  background:#f2f6ff;
}
.hero h2{
  margin:0 0 16px;
  font-size:2rem;
}
.tagline{
  max-width:640px;
  margin:0 auto;
  font-size:1.1rem;
}
.btn{
  display:inline-block;
  margin-top:32px;
  padding:12px 24px;
  background:#0078ff;
  color:#fff;
  text-decoration:none;
  border-radius:6px;
  transition:background .3s;
}
.btn:hover{
  background:#005fcc;
}
/* 主要内容 */
.content{
  max-width:840px;
  margin:56px auto;
  padding:0 24px;
}
.content h2{
  margin-top:0;
}
/* 页脚 */
footer{
  text-align:center;
  padding:24px;
  background:#f9f9f9;
  font-size:.9rem;
  color:#666;
}