/* Reset & Base */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
:root{
  --primary:#1a56db;
  --primary-dark:#1e40af;
  --primary-light:#dbeafe;
  --bg:#ffffff;
  --bg-alt:#f8fafc;
  --bg-card:#ffffff;
  --text:#1e293b;
  --text-light:#5b6578;
  --text-lighter:#6b7280;
  --border:#e2e8f0;
  --shadow:0 1px 3px rgba(0,0,0,0.1);
  --shadow-md:0 4px 6px -1px rgba(0,0,0,0.1);
  --shadow-lg:0 10px 15px -3px rgba(0,0,0,0.1);
  --radius:8px;
  --radius-lg:12px;
  --max-width:1200px;
  --header-height:64px;
  --font:'Inter',system-ui,-apple-system,sans-serif;
}
html.dark{
  --bg:#0f172a;
  --bg-alt:#1e293b;
  --bg-card:#1e293b;
  --text:#e2e8f0;
  --text-light:#94a3b8;
  --text-lighter:#9ca3af;
  --border:#334155;
  --shadow:0 1px 3px rgba(0,0,0,0.3);
  --shadow-md:0 4px 6px -1px rgba(0,0,0,0.3);
  --shadow-lg:0 10px 15px -3px rgba(0,0,0,0.3);
  --primary-light:#1e3a5f;
}
html{scroll-behavior:smooth;font-size:16px}
body{font-family:var(--font);color:var(--text);background:var(--bg);line-height:1.7;min-height:100vh;display:flex;flex-direction:column;transition:background .3s,color .3s}
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}
.skip-link{position:absolute;top:-100%;left:0;background:var(--primary);color:#fff;padding:8px 16px;z-index:9999;border-radius:0 0 var(--radius) 0}
.skip-link:focus{top:0}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}

/* Container */
.container{max-width:var(--max-width);margin:0 auto;padding:0 1rem}

/* Header */
.site-header{background:var(--bg);border-bottom:1px solid var(--border);position:sticky;top:0;z-index:100;height:var(--header-height);display:flex;align-items:center;transition:background .3s}
.header-inner{display:flex;align-items:center;justify-content:space-between;width:100%;max-width:var(--max-width);margin:0 auto;padding:0 1rem}
.site-logo{font-size:1.25rem;font-weight:700;color:var(--text);display:flex;align-items:center;gap:8px}
.site-logo:hover{text-decoration:none;color:var(--primary)}
.site-logo svg{width:32px;height:32px}
.nav-links{display:flex;gap:1.5rem;align-items:center;list-style:none}
.nav-links a{color:var(--text-light);font-weight:500;font-size:.95rem;padding:4px 0;border-bottom:2px solid transparent;transition:all .2s}
.nav-links a:hover,.nav-links a.active{color:var(--primary);text-decoration:none;border-bottom-color:var(--primary)}
.menu-toggle{display:none;background:none;border:none;cursor:pointer;padding:8px;color:var(--text)}
.menu-toggle svg{width:24px;height:24px}

/* Hero */
.hero{background:linear-gradient(135deg,var(--primary),#2563eb);color:#fff;padding:4rem 0;text-align:center}
.hero h1{font-size:2.5rem;font-weight:700;margin-bottom:1rem;line-height:1.2}
.hero p{font-size:1.2rem;opacity:.9;max-width:600px;margin:0 auto 2rem}
.hero-buttons{display:flex;gap:1rem;justify-content:center;flex-wrap:wrap}
.btn{display:inline-flex;align-items:center;gap:8px;padding:12px 24px;border-radius:var(--radius);font-weight:600;font-size:1rem;border:none;cursor:pointer;transition:all .2s;text-decoration:none}
.btn:hover{text-decoration:none;transform:translateY(-1px)}
.btn-white{background:#fff;color:var(--primary)}
.btn-white:hover{background:#f0f4ff;color:var(--primary)}
.btn-outline{background:transparent;color:#fff;border:2px solid rgba(255,255,255,.5)}
.btn-outline:hover{background:rgba(255,255,255,.1);color:#fff}
.btn-primary{background:var(--primary);color:#fff}
.btn-primary:hover{background:var(--primary-dark);color:#fff}

/* Info boxes */
.info-boxes{display:grid;grid-template-columns:repeat(auto-fit,minmax(250px,1fr));gap:1.5rem;padding:3rem 0}
.info-box{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);padding:2rem;text-align:center;transition:box-shadow .2s}
.info-box:hover{box-shadow:var(--shadow-md)}
.info-box-icon{width:48px;height:48px;background:var(--primary-light);border-radius:50%;display:flex;align-items:center;justify-content:center;margin:0 auto 1rem;color:var(--primary)}
.info-box h3{font-size:1.1rem;margin-bottom:.5rem}
.info-box p{color:var(--text-light);font-size:.95rem}

/* Articles Grid */
.section-title{font-size:1.75rem;font-weight:700;margin-bottom:2rem;text-align:center}
.articles-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(340px,1fr));gap:1.5rem;padding-bottom:3rem}
.article-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);overflow:hidden;transition:box-shadow .2s,transform .2s}
.article-card:hover{box-shadow:var(--shadow-md);transform:translateY(-2px)}
.article-card-body{padding:1.5rem}
.article-card-meta{font-size:.85rem;color:var(--text-lighter);margin-bottom:.5rem;display:flex;gap:1rem}
.article-card h2{font-size:1.15rem;margin-bottom:.75rem;line-height:1.4}
.article-card h2 a{color:var(--text)}
.article-card h2 a:hover{color:var(--primary)}
.article-card p{color:var(--text-light);font-size:.95rem;line-height:1.6}
.article-tags{display:flex;flex-wrap:wrap;gap:.5rem;margin-top:1rem}
.tag{display:inline-block;padding:4px 10px;background:var(--primary-light);color:var(--primary);border-radius:20px;font-size:.8rem;font-weight:500}
html.dark .tag{background:rgba(26,86,219,.2)}

/* Single Article */
.article-single{max-width:800px;margin:0 auto;padding:2rem 1rem}
.article-header{margin-bottom:2rem}
.article-header h1{font-size:2rem;line-height:1.3;margin-bottom:1rem}
.article-meta{display:flex;gap:1rem;color:var(--text-light);font-size:.9rem;flex-wrap:wrap}
.breadcrumb{display:flex;gap:.5rem;align-items:center;font-size:.9rem;color:var(--text-light);margin-bottom:1.5rem;flex-wrap:wrap}
.breadcrumb a{color:var(--text-light)}
.breadcrumb a:hover{color:var(--primary)}
.breadcrumb-sep{color:var(--text-lighter)}

/* Table of Contents */
.toc{background:var(--bg-alt);border:1px solid var(--border);border-radius:var(--radius);padding:1.5rem;margin-bottom:2rem}
.toc-title{font-weight:600;margin-bottom:.75rem;font-size:1.05rem}
.toc ul{list-style:none;padding-left:1rem}
.toc li{margin:.4rem 0}
.toc a{color:var(--text-light);font-size:.9rem}
.toc a:hover{color:var(--primary)}

/* Article Content */
.article-content{font-size:1.05rem;line-height:1.8}
.article-content h2{font-size:1.5rem;margin:2rem 0 1rem;padding-top:1rem;border-top:1px solid var(--border)}
.article-content h3{font-size:1.25rem;margin:1.5rem 0 .75rem}
.article-content p{margin-bottom:1.25rem}
.article-content ul,.article-content ol{margin-bottom:1.25rem;padding-left:1.5rem}
.article-content li{margin-bottom:.5rem}
.article-content blockquote{border-left:4px solid var(--primary);padding:1rem 1.5rem;margin:1.5rem 0;background:var(--bg-alt);border-radius:0 var(--radius) var(--radius) 0}
.article-content table{width:100%;border-collapse:collapse;margin:1.5rem 0;font-size:.95rem}
.article-content th,.article-content td{padding:.75rem 1rem;border:1px solid var(--border);text-align:left}
.article-content th{background:var(--bg-alt);font-weight:600}
.article-content code{background:var(--bg-alt);padding:2px 6px;border-radius:4px;font-size:.9em}
.article-content pre{background:var(--bg-alt);padding:1.5rem;border-radius:var(--radius);overflow-x:auto;margin:1.5rem 0}
.article-content pre code{background:none;padding:0}
.article-content img{border-radius:var(--radius);margin:1.5rem 0}
.article-content a{text-decoration:underline}

/* FAQ */
.faq-section{margin:2rem 0}
.faq-item{border:1px solid var(--border);border-radius:var(--radius);margin-bottom:1rem;overflow:hidden}
.faq-question{padding:1rem 1.5rem;font-weight:600;cursor:pointer;display:flex;justify-content:space-between;align-items:center;background:var(--bg-alt);user-select:none}
.faq-question::after{content:'+';font-size:1.25rem;font-weight:400;transition:transform .2s}
.faq-item.open .faq-question::after{content:'−'}
.faq-answer{padding:0 1.5rem;max-height:0;overflow:hidden;transition:max-height .3s,padding .3s}
.faq-item.open .faq-answer{padding:1rem 1.5rem;max-height:500px}

/* CTA Box */
.cta-box{background:linear-gradient(135deg,var(--primary),#2563eb);color:#fff;padding:2rem;border-radius:var(--radius-lg);margin:2rem 0;text-align:center}
.cta-box h3{font-size:1.3rem;margin-bottom:.75rem}
.cta-box p{opacity:.9;margin-bottom:1rem}
.cta-box .btn{background:#fff;color:var(--primary)}

/* Pagination */
.pagination{display:flex;justify-content:center;gap:.5rem;padding:2rem 0}
.pagination a,.pagination span{padding:8px 16px;border:1px solid var(--border);border-radius:var(--radius);color:var(--text-light);font-size:.9rem}
.pagination a:hover{background:var(--primary-light);color:var(--primary);text-decoration:none}
.pagination .active{background:var(--primary);color:#fff;border-color:var(--primary)}

/* Footer */
.site-footer{background:var(--bg-alt);border-top:1px solid var(--border);padding:3rem 0 1.5rem;margin-top:auto}
.footer-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:2rem;margin-bottom:2rem}
.footer-col h4{font-weight:600;margin-bottom:1rem;font-size:.95rem}
.footer-col ul{list-style:none}
.footer-col li{margin:.5rem 0}
.footer-col a{color:var(--text-light);font-size:.9rem}
.footer-col a:hover{color:var(--primary)}
.footer-bottom{text-align:center;color:var(--text-lighter);font-size:.85rem;padding-top:1.5rem;border-top:1px solid var(--border)}

/* Chat Widget */
.chat-widget-btn{position:fixed;bottom:24px;right:24px;width:56px;height:56px;background:var(--primary);color:#fff;border:none;border-radius:50%;cursor:pointer;box-shadow:var(--shadow-lg);z-index:1000;display:flex;align-items:center;justify-content:center;transition:transform .2s}
.chat-widget-btn:hover{transform:scale(1.1)}
.chat-widget-btn svg{width:24px;height:24px}
.chat-widget{position:fixed;bottom:90px;right:24px;width:380px;height:500px;background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);box-shadow:var(--shadow-lg);z-index:1000;display:none;flex-direction:column;overflow:hidden}
.chat-widget.open{display:flex}
.chat-widget-header{background:var(--primary);color:#fff;padding:12px 16px;display:flex;justify-content:space-between;align-items:center}
.chat-widget-header h4{font-size:.95rem}
.chat-widget-close{background:none;border:none;color:#fff;cursor:pointer;font-size:1.25rem;padding:0;line-height:1}
.chat-widget-messages{flex:1;overflow-y:auto;padding:12px;font-size:.9rem}
.chat-widget-input{display:flex;gap:8px;padding:12px;border-top:1px solid var(--border)}
.chat-widget-input input{flex:1;padding:8px 12px;border:1px solid var(--border);border-radius:var(--radius);font-size:.9rem;background:var(--bg);color:var(--text)}
.chat-widget-input button{padding:8px 16px;background:var(--primary);color:#fff;border:none;border-radius:var(--radius);cursor:pointer;font-weight:500}

/* Chat Page */
.chat-page{height:calc(100vh - var(--header-height));display:flex;flex-direction:column;max-width:900px;margin:0 auto;padding:0 1rem}
.chat-controls{display:flex;gap:1rem;padding:1rem 0;align-items:center;flex-wrap:wrap;border-bottom:1px solid var(--border)}
.chat-controls select,.chat-controls button{padding:8px 12px;border:1px solid var(--border);border-radius:var(--radius);background:var(--bg);color:var(--text);font-size:.9rem;cursor:pointer}
.chat-controls button{background:var(--primary);color:#fff;border-color:var(--primary);font-weight:500}
.chat-messages{flex:1;overflow-y:auto;padding:1rem 0}
.chat-msg{margin-bottom:1.5rem;display:flex;gap:12px}
.chat-msg-user{justify-content:flex-end}
.chat-msg-avatar{width:32px;height:32px;border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:.85rem;font-weight:600;flex-shrink:0}
.chat-msg-user .chat-msg-avatar{background:var(--primary);color:#fff}
.chat-msg-ai .chat-msg-avatar{background:var(--bg-alt);color:var(--primary);border:1px solid var(--border)}
.chat-msg-content{max-width:75%;padding:12px 16px;border-radius:var(--radius-lg);line-height:1.6;font-size:.95rem;position:relative}
.chat-msg-user .chat-msg-content{background:var(--primary);color:#fff;border-bottom-right-radius:4px}
.chat-msg-ai .chat-msg-content{background:var(--bg-alt);border:1px solid var(--border);border-bottom-left-radius:4px}
.chat-msg-content .copy-btn{position:absolute;top:4px;right:4px;background:none;border:none;cursor:pointer;opacity:0;transition:opacity .2s;padding:4px;font-size:.75rem;color:var(--text-light)}
.chat-msg-content:hover .copy-btn{opacity:1}
.think-block{background:rgba(26,86,219,.08);border-left:3px solid var(--primary);padding:8px 12px;margin:8px 0;border-radius:0 var(--radius) var(--radius) 0;font-size:.85rem}
.think-toggle{cursor:pointer;color:var(--primary);font-weight:500;font-size:.85rem;display:flex;align-items:center;gap:4px;user-select:none}
.think-content{max-height:0;overflow:hidden;transition:max-height .3s}
.think-block.open .think-content{max-height:2000px}
.chat-input-area{display:flex;gap:8px;padding:1rem 0;border-top:1px solid var(--border)}
.chat-input-area textarea{flex:1;padding:12px;border:1px solid var(--border);border-radius:var(--radius);resize:none;font-family:var(--font);font-size:.95rem;min-height:48px;max-height:150px;background:var(--bg);color:var(--text)}
.chat-input-area button{padding:12px 24px;background:var(--primary);color:#fff;border:none;border-radius:var(--radius);cursor:pointer;font-weight:600;align-self:flex-end}
.chat-input-area button:disabled{opacity:.5;cursor:not-allowed}
.chat-sidebar{border-right:1px solid var(--border);width:250px;overflow-y:auto;padding:1rem}
.chat-sidebar-item{padding:8px 12px;border-radius:var(--radius);cursor:pointer;font-size:.9rem;margin-bottom:4px;display:flex;justify-content:space-between;align-items:center}
.chat-sidebar-item:hover,.chat-sidebar-item.active{background:var(--primary-light)}
.chat-sidebar-item .del-btn{opacity:0;background:none;border:none;cursor:pointer;color:var(--text-light);font-size:.8rem}
.chat-sidebar-item:hover .del-btn{opacity:1}
.chat-layout{display:flex;height:calc(100vh - var(--header-height))}

/* Admin */
.admin-page{max-width:900px;margin:0 auto;padding:2rem 1rem}
.admin-section{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);padding:1.5rem;margin-bottom:1.5rem}
.admin-section h2{font-size:1.2rem;margin-bottom:1rem;padding-bottom:.75rem;border-bottom:1px solid var(--border)}
.form-group{margin-bottom:1rem}
.form-group label{display:block;font-weight:500;margin-bottom:.5rem;font-size:.9rem}
.form-group input,.form-group select,.form-group textarea{width:100%;padding:8px 12px;border:1px solid var(--border);border-radius:var(--radius);font-size:.9rem;background:var(--bg);color:var(--text)}
.form-group textarea{min-height:80px;font-family:var(--font)}
.form-actions{display:flex;gap:.5rem}
.login-box{max-width:400px;margin:4rem auto;text-align:center;padding:2rem}

/* Dark mode toggle */
.dark-toggle{position:fixed;bottom:24px;left:24px;width:44px;height:44px;border-radius:50%;background:var(--bg-card);border:1px solid var(--border);cursor:pointer;display:flex;align-items:center;justify-content:center;z-index:1000;box-shadow:var(--shadow);transition:all .2s}
.dark-toggle:hover{box-shadow:var(--shadow-md)}
.dark-toggle svg{width:20px;height:20px;color:var(--text)}

/* 404 */
.error-page{text-align:center;padding:6rem 1rem}
.error-page h1{font-size:6rem;font-weight:700;color:var(--primary);line-height:1}
.error-page p{font-size:1.2rem;color:var(--text-light);margin:1rem 0 2rem}

/* Blog listing */
.blog-header{padding:2rem 0;text-align:center}
.blog-header h1{font-size:2rem;margin-bottom:.5rem}
.blog-header p{color:var(--text-light)}

/* Page */
.page-single{max-width:800px;margin:0 auto;padding:2rem 1rem}
.page-single h1{font-size:2rem;margin-bottom:1.5rem}
.page-content{line-height:1.8}
.page-content h2{font-size:1.4rem;margin:2rem 0 1rem}
.page-content p{margin-bottom:1rem}
.page-content ul,.page-content ol{margin-bottom:1rem;padding-left:1.5rem}
.page-content li{margin-bottom:.5rem}

/* Stats chart */
.stats-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(180px,1fr));gap:1rem;margin-bottom:1.5rem}
.stat-card{background:var(--bg-alt);padding:1.25rem;border-radius:var(--radius);text-align:center}
.stat-card .stat-value{font-size:1.75rem;font-weight:700;color:var(--primary)}
.stat-card .stat-label{font-size:.85rem;color:var(--text-light)}

/* Toggle switch */
.toggle-switch{position:relative;width:48px;height:24px;display:inline-block}
.toggle-switch input{opacity:0;width:0;height:0}
.toggle-slider{position:absolute;cursor:pointer;inset:0;background:var(--border);border-radius:24px;transition:.3s}
.toggle-slider::before{content:'';position:absolute;width:18px;height:18px;left:3px;bottom:3px;background:#fff;border-radius:50%;transition:.3s}
.toggle-switch input:checked+.toggle-slider{background:var(--primary)}
.toggle-switch input:checked+.toggle-slider::before{transform:translateX(24px)}

/* Responsive */
@media(max-width:768px){
  .hero h1{font-size:1.75rem}
  .hero p{font-size:1rem}
  .articles-grid{grid-template-columns:1fr}
  .nav-links{display:none;position:absolute;top:var(--header-height);left:0;right:0;background:var(--bg);border-bottom:1px solid var(--border);flex-direction:column;padding:1rem;gap:.5rem}
  .nav-links.open{display:flex}
  .menu-toggle{display:block}
  .chat-widget{width:calc(100% - 32px);right:16px;bottom:80px;height:60vh}
  .chat-layout{flex-direction:column}
  .chat-sidebar{width:100%;height:auto;max-height:150px;border-right:none;border-bottom:1px solid var(--border)}
  .footer-grid{grid-template-columns:1fr 1fr}
  .article-header h1{font-size:1.5rem}
  .chat-msg-content{max-width:85%}
}
@media(max-width:480px){
  .hero-buttons{flex-direction:column;align-items:center}
  .footer-grid{grid-template-columns:1fr}
  .info-boxes{grid-template-columns:1fr}
}

/* Related articles */
.related-articles a{transition:box-shadow .2s,transform .2s}
.related-articles a:hover{box-shadow:var(--shadow-md);transform:translateY(-1px);text-decoration:none}

/* Print styles */
@media print{
  .site-header,.site-footer,.chat-widget-btn,.chat-widget,.dark-toggle,.toc,.chat-controls,.chat-input-area,.chat-sidebar{display:none!important}
  .article-single{max-width:100%;padding:0}
  body{color:#000;background:#fff}
  a{color:#000;text-decoration:underline}
}