/* ============================================
   爱思助手官网 - 共享样式表
   设计令牌分层：颜色 / 间距 / z-index / 动画
   ============================================ */

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

/* --- 设计令牌：颜色 --- */
:root{
  --bg:#0a0e1a;
  --bg-card:#131825;
  --bg-card-hover:#1a2138;
  --border:#1e2a3d;
  --text:#e8edf5;
  --text-muted:#8b9bb4;
  --blue:#007AFF;
  --purple:#A048ED;
  --gradient:linear-gradient(135deg,#A048ED 0%,#007AFF 100%);
  --gradient-soft:linear-gradient(135deg,rgba(160,72,237,.1),rgba(0,122,255,.1));
  --radius:16px;
  --warn:#ff9f1c;
  --success:#28c840;
  --danger:#ff5f57;
}

/* --- 设计令牌：z-index --- */
:root{
  --z-nav:100;
  --z-quicknav:50;
  --z-overlay:200;
}

/* --- 基础排版 --- */
html{scroll-behavior:smooth;font-size:16px}
body{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",sans-serif;background:var(--bg);color:var(--text);line-height:1.7;overflow-x:hidden}
a{color:inherit;text-decoration:none}
img,svg{max-width:100%;display:block}

/* --- 布局容器 --- */
.container{max-width:1200px;margin:0 auto;padding:0 24px}

/* --- 导航栏 --- */
.nav{position:fixed;top:0;left:0;right:0;z-index:var(--z-nav);background:rgba(10,14,26,.85);backdrop-filter:blur(20px);border-bottom:1px solid var(--border);transition:background .3s}
.nav .container{display:flex;align-items:center;justify-content:space-between;height:68px}
.nav-logo{display:flex;align-items:center;gap:10px;font-weight:700;font-size:20px}
.nav-logo img{width:36px;height:36px}
.nav-links{display:flex;gap:8px;align-items:center}
.nav-links a{padding:8px 16px;border-radius:8px;font-size:15px;color:var(--text-muted);transition:all .2s}
.nav-links a:hover,.nav-links a.active{color:var(--text);background:var(--bg-card)}
.nav-cta{padding:8px 20px!important;background:var(--gradient);color:#fff!important;border-radius:8px;font-weight:600}
.nav-toggle{display:none;background:none;border:none;color:var(--text);font-size:24px;cursor:pointer}

/* --- 按钮 --- */
.btn{display:inline-flex;align-items:center;gap:8px;padding:14px 32px;border-radius:12px;font-size:16px;font-weight:600;transition:all .3s;cursor:pointer;border:none}
.btn-primary{background:var(--gradient);color:#fff;box-shadow:0 8px 32px rgba(0,122,255,.3)}
.btn-primary:hover{transform:translateY(-2px);box-shadow:0 12px 40px rgba(0,122,255,.4)}
.btn-secondary{background:var(--bg-card);color:var(--text);border:1px solid var(--border)}
.btn-secondary:hover{background:var(--bg-card-hover);border-color:var(--blue)}

/* --- 徽章 --- */
.badge{display:inline-flex;align-items:center;gap:8px;padding:6px 16px;background:var(--gradient-soft);border:1px solid rgba(0,122,255,.2);border-radius:20px;font-size:13px;color:var(--blue);margin-bottom:20px}

/* --- 内页 Hero --- */
.page-hero{padding:130px 0 50px;text-align:center;position:relative;overflow:hidden}
.page-hero::before{content:'';position:absolute;top:-100px;left:50%;transform:translateX(-50%);width:600px;height:400px;background:radial-gradient(ellipse,rgba(160,72,237,.1),transparent 70%);pointer-events:none}
.page-hero h1{font-size:42px;font-weight:800;margin-bottom:16px;position:relative}
.page-hero p{font-size:18px;color:var(--text-muted);max-width:600px;margin:0 auto;position:relative}

/* --- 通用区块 --- */
.section{padding:80px 0}
.section-header{text-align:center;margin-bottom:48px}
.section-header h2{font-size:36px;font-weight:800;margin-bottom:12px}
.section-header p{font-size:17px;color:var(--text-muted);max-width:600px;margin:0 auto}

/* --- 滚动淡入动画 --- */
.fade-in{opacity:0;transform:translateY(30px);transition:opacity .6s,transform .6s}
.fade-in.visible{opacity:1;transform:translateY(0)}

/* --- 页脚 --- */
.footer{background:var(--bg-card);border-top:1px solid var(--border);padding:56px 0 24px}
.footer-grid{display:grid;grid-template-columns:2fr 1fr 1fr 1fr;gap:40px;margin-bottom:40px}
.footer-brand p{color:var(--text-muted);font-size:14px;margin-top:12px;max-width:300px}
.footer-col h4{font-size:15px;font-weight:700;margin-bottom:16px}
.footer-col ul{list-style:none}
.footer-col ul li{margin-bottom:10px}
.footer-col ul li a{color:var(--text-muted);font-size:14px;transition:color .2s}
.footer-col ul li a:hover{color:var(--blue)}
.footer-bottom{border-top:1px solid var(--border);padding-top:24px;display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:12px}
.footer-bottom p{color:var(--text-muted);font-size:13px}
.footer-icp{display:flex;gap:16px;flex-wrap:wrap}
.footer-icp a{color:var(--text-muted);font-size:13px}
.footer-icp a:hover{color:var(--blue)}

/* --- 无障碍：焦点样式 --- */
a:focus-visible,button:focus-visible,.faq-question:focus-visible,.faq-cat:focus-visible,.dl-btn:focus-visible,.nav-toggle:focus-visible{
  outline:2px solid var(--blue);
  outline-offset:2px;
  border-radius:4px;
}

/* --- 无障碍：降低动画偏好 --- */
@media(prefers-reduced-motion:reduce){
  *{animation-duration:.01ms!important;transition-duration:.01ms!important;scroll-behavior:auto!important}
  .fade-in{opacity:1;transform:none}
}

/* --- 响应式 --- */
@media(max-width:900px){
  .nav-links{display:none;position:absolute;top:68px;left:0;right:0;background:var(--bg-card);flex-direction:column;padding:16px;border-bottom:1px solid var(--border)}
  .nav-links.show{display:flex}
  .nav-toggle{display:block}
  .nav-links a{width:100%}
  .footer-grid{grid-template-columns:1fr 1fr;gap:32px}
  .page-hero h1{font-size:28px}
}
@media(max-width:480px){
  .footer-grid{grid-template-columns:1fr}
}