*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
:root{
  --primary:#1a8cff;
  --primary-dark:#0d6fd4;
  --accent:#00c9a7;
  --bg:#f5f8fc;
  --card:#fff;
  --text:#1a1a2e;
  --text-light:#5a6278;
  --border:#e2e8f0;
  --shadow:0 4px 24px rgba(26,140,255,.08);
  --radius:12px;
  --max:1200px;
}
html{scroll-behavior:smooth;font-size:16px}
body{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;color:var(--text);background:var(--bg);line-height:1.8}
a{color:var(--primary);text-decoration:none;transition:color .2s}
a:hover{color:var(--primary-dark);text-decoration:underline}
img{max-width:100%;height:auto;display:block}
.container{max-width:var(--max);margin:0 auto;padding:0 20px}

/* Header */
.site-header{background:var(--card);box-shadow:0 2px 12px rgba(0,0,0,.06);position:sticky;top:0;z-index:100}
.header-inner{display:flex;align-items:center;justify-content:space-between;padding:12px 20px;max-width:var(--max);margin:0 auto}
.logo{display:flex;align-items:center;gap:10px;font-size:1.25rem;font-weight:700;color:var(--text);text-decoration:none}
.logo:hover{text-decoration:none;color:var(--primary)}
.logo img{width:40px;height:40px;border-radius:10px}
.nav-menu{display:flex;gap:28px;list-style:none}
.nav-menu a{color:var(--text);font-weight:500;font-size:.95rem}
.nav-menu a:hover,.nav-menu a.active{color:var(--primary);text-decoration:none}
.menu-toggle{display:none;background:none;border:none;cursor:pointer;padding:8px}
.menu-toggle span{display:block;width:24px;height:2px;background:var(--text);margin:5px 0;transition:.3s}

/* Hero */
.hero{background:linear-gradient(135deg,#1a8cff 0%,#00c9a7 100%);color:#fff;padding:60px 20px;text-align:center}
.hero h1{font-size:2rem;margin-bottom:16px;line-height:1.4}
.hero p{font-size:1.1rem;opacity:.92;max-width:700px;margin:0 auto 28px}
.btn-group{display:flex;gap:16px;justify-content:center;flex-wrap:wrap}
.btn{display:inline-flex;align-items:center;gap:8px;padding:14px 32px;border-radius:50px;font-weight:600;font-size:1rem;border:none;cursor:pointer;transition:transform .2s,box-shadow .2s;text-decoration:none}
.btn:hover{transform:translateY(-2px);text-decoration:none}
.btn-primary{background:#fff;color:var(--primary);box-shadow:0 4px 16px rgba(0,0,0,.15)}
.btn-primary:hover{color:var(--primary-dark)}
.btn-outline{background:transparent;color:#fff;border:2px solid rgba(255,255,255,.7)}
.btn-outline:hover{background:rgba(255,255,255,.15);color:#fff}

/* Sections */
section{padding:60px 0}
.section-title{text-align:center;margin-bottom:40px}
.section-title h2{font-size:1.75rem;margin-bottom:10px;color:var(--text)}
.section-title p{color:var(--text-light);max-width:600px;margin:0 auto}
.section-alt{background:var(--card)}

/* Feature Grid */
.feature-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:28px}
.feature-card{background:var(--card);border-radius:var(--radius);padding:28px;box-shadow:var(--shadow);transition:transform .2s}
.feature-card:hover{transform:translateY(-4px)}
.feature-card h3{font-size:1.15rem;margin-bottom:10px;color:var(--primary)}
.feature-card p{color:var(--text-light);font-size:.95rem}

/* Content blocks */
.content-block{display:grid;grid-template-columns:1fr 1fr;gap:40px;align-items:center;margin-bottom:48px}
.content-block.reverse{direction:rtl}
.content-block.reverse>*{direction:ltr}
.content-block img{border-radius:var(--radius);box-shadow:var(--shadow)}
.content-block h3{font-size:1.35rem;margin-bottom:14px;color:var(--text)}
.content-block p{color:var(--text-light);margin-bottom:12px}

/* Steps */
.steps{display:grid;grid-template-columns:repeat(4,1fr);gap:24px}
.step{text-align:center;padding:24px 16px}
.step-num{width:48px;height:48px;background:var(--primary);color:#fff;border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:1.25rem;font-weight:700;margin:0 auto 16px}
.step h4{margin-bottom:8px}
.step p{color:var(--text-light);font-size:.9rem}

/* FAQ */
.faq-list{max-width:800px;margin:0 auto}
.faq-item{background:var(--card);border-radius:var(--radius);margin-bottom:12px;box-shadow:var(--shadow);overflow:hidden}
.faq-q{padding:18px 24px;font-weight:600;cursor:pointer;display:flex;justify-content:space-between;align-items:center}
.faq-q::after{content:"+";font-size:1.25rem;color:var(--primary)}
.faq-item.open .faq-q::after{content:"−"}
.faq-a{padding:0 24px 18px;color:var(--text-light);display:none}
.faq-item.open .faq-a{display:block}

/* Article */
.article{max-width:860px;margin:0 auto;padding:40px 20px}
.article h1{font-size:1.75rem;margin-bottom:20px}
.article h2{font-size:1.35rem;margin:32px 0 14px;color:var(--text)}
.article h3{font-size:1.1rem;margin:24px 0 10px}
.article p{margin-bottom:14px;color:var(--text-light)}
.article ul,.article ol{margin:0 0 16px 24px;color:var(--text-light)}
.article li{margin-bottom:6px}
.article img{margin:20px auto;border-radius:var(--radius);box-shadow:var(--shadow)}

/* Breadcrumb */
.breadcrumb{padding:16px 0;font-size:.9rem;color:var(--text-light)}
.breadcrumb a{color:var(--primary)}

/* Footer */
.site-footer{background:#1a1a2e;color:rgba(255,255,255,.75);padding:48px 0 24px}
.footer-grid{display:grid;grid-template-columns:2fr 1fr 1fr 1fr;gap:32px;margin-bottom:32px}
.footer-grid h4{color:#fff;margin-bottom:16px;font-size:1rem}
.footer-grid p,.footer-grid a{color:rgba(255,255,255,.65);font-size:.9rem;line-height:2}
.footer-grid a:hover{color:#fff;text-decoration:none}
.footer-bottom{text-align:center;padding-top:24px;border-top:1px solid rgba(255,255,255,.1);font-size:.85rem}

/* Error pages */
.error-page{min-height:70vh;display:flex;align-items:center;justify-content:center;text-align:center;padding:40px 20px}
.error-page h1{font-size:5rem;color:var(--primary);margin-bottom:8px}
.error-page h2{margin-bottom:16px}
.error-page p{color:var(--text-light);margin-bottom:24px}

/* Internal links */
.internal-links{display:flex;flex-wrap:wrap;gap:12px;margin:24px 0}
.internal-links a{background:var(--card);padding:8px 16px;border-radius:20px;font-size:.9rem;box-shadow:var(--shadow);text-decoration:none}
.internal-links a:hover{background:var(--primary);color:#fff}

/* Responsive */
@media(max-width:992px){
  .feature-grid{grid-template-columns:repeat(2,1fr)}
  .content-block{grid-template-columns:1fr}
  .content-block.reverse{direction:ltr}
  .steps{grid-template-columns:repeat(2,1fr)}
  .footer-grid{grid-template-columns:repeat(2,1fr)}
}
@media(max-width:768px){
  .nav-menu{display:none;position:absolute;top:100%;left:0;right:0;background:var(--card);flex-direction:column;padding:16px 20px;gap:0;box-shadow:0 8px 24px rgba(0,0,0,.1)}
  .nav-menu.open{display:flex}
  .nav-menu li{border-bottom:1px solid var(--border)}
  .nav-menu a{display:block;padding:12px 0}
  .menu-toggle{display:block}
  .hero h1{font-size:1.5rem}
  .hero{padding:40px 20px}
  .feature-grid{grid-template-columns:1fr}
  .steps{grid-template-columns:1fr}
  .footer-grid{grid-template-columns:1fr}
  section{padding:40px 0}
}