/* ExpertLab - Knowledge Graph Navigation, Dell-inspired dark-purple tech design */
:root {
  --bg:       #0d0d14;
  --surface:  #14141f;
  --surface2: #1a1a28;
  --border:   #2a2a3a;
  --accent:   #7c3aed;
  --accent2:  #a78bfa;
  --text:     #e2e2f0;
  --text-m:   #a1a1b8;
  --text-sm:  #6b6b88;
  --red:      #f87171;
  --green:    #4ade80;
  --font:     'Inter', system-ui, sans-serif;
  --mono:     'JetBrains Mono', 'Fira Code', monospace;
  --radius:   6px;
  --max:      1180px;
  --shadow:   0 2px 16px rgba(124,58,237,0.10);
}
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:var(--font);background:var(--bg);color:var(--text);font-size:16px;line-height:1.65;min-height:100vh}
img{max-width:100%;height:auto;display:block}
a{color:var(--accent2);text-decoration:none;transition:color .15s}
a:hover{color:#fff}
ul,ol{padding-left:1.4em}

/* Container */
.container{max-width:var(--max);margin:0 auto;padding:0 20px}

/* Header */
.el-header{background:var(--surface);border-bottom:1px solid var(--border);position:sticky;top:0;z-index:100}
.el-header-row{display:flex;align-items:center;gap:24px;padding-top:14px;padding-bottom:14px}
.el-brand{display:flex;align-items:center;gap:10px;font-weight:700;font-size:1.1rem;color:var(--text);text-decoration:none}
.el-brand-sm{font-size:0.95rem}
.el-brand-icon{background:var(--accent);color:#fff;font-weight:800;border-radius:4px;padding:2px 7px;font-size:0.85rem;letter-spacing:0.04em}
.el-nav{margin-left:auto}
.el-nav ul{list-style:none;display:flex;gap:6px;padding:0}
.el-nav a{color:var(--text-m);padding:6px 12px;border-radius:var(--radius);font-size:0.88rem;display:block;transition:background .15s,color .15s}
.el-nav a:hover,.el-nav a.el-active{background:rgba(124,58,237,0.15);color:var(--text)}
.el-toggle{display:none;background:none;border:1px solid var(--border);color:var(--text);padding:6px 10px;border-radius:var(--radius);cursor:pointer;font-size:1.1rem;margin-left:auto}

/* Breadcrumb */
.el-breadcrumb-wrap{background:var(--surface2);border-bottom:1px solid var(--border);padding:8px 0}
.el-breadcrumb{display:flex;align-items:center;gap:6px;font-size:0.82rem;flex-wrap:wrap}
.el-breadcrumb a{color:var(--accent2)}
.el-breadcrumb span{color:var(--text-sm)}
.el-bc-curr{color:var(--text-m)}

/* Hero */
.el-hero{background:linear-gradient(135deg,#0d0d14 0%,#1a1030 50%,#0d0d14 100%);border-bottom:1px solid var(--border);padding:72px 0 56px;position:relative;overflow:hidden}
.el-hero::before{content:'';position:absolute;right:-80px;top:-80px;width:400px;height:400px;background:radial-gradient(circle,rgba(124,58,237,0.18) 0%,transparent 70%);pointer-events:none}
.el-hero-inner{display:grid;grid-template-columns:1fr 1fr;gap:48px;align-items:center}
.el-hero-tag{display:inline-block;background:rgba(124,58,237,0.2);color:var(--accent2);border:1px solid rgba(124,58,237,0.3);border-radius:30px;padding:4px 14px;font-size:0.78rem;font-weight:600;letter-spacing:0.08em;text-transform:uppercase;margin-bottom:16px}
.el-hero h1{font-size:clamp(1.8rem,4vw,2.8rem);font-weight:700;line-height:1.18;margin-bottom:16px}
.el-hero h1 em{font-style:normal;color:var(--accent2)}
.el-hero-desc{font-size:1.05rem;color:var(--text-m);max-width:480px;margin-bottom:24px}
.el-hero-meta{display:flex;gap:24px;font-size:0.82rem;color:var(--text-sm)}
.el-hero-meta span{display:flex;align-items:center;gap:6px}
.el-hero-img{border-radius:var(--radius);overflow:hidden;border:1px solid var(--border);box-shadow:var(--shadow)}
.el-hero-img img{width:100%;height:280px;object-fit:cover}

/* Knowledge Graph section */
.el-graph{padding:56px 0}
.el-graph-label{text-align:center;margin-bottom:8px}
.el-graph-label span{display:inline-block;background:rgba(124,58,237,0.12);color:var(--accent2);border:1px solid rgba(124,58,237,0.25);border-radius:20px;padding:3px 12px;font-size:0.76rem;letter-spacing:0.07em;text-transform:uppercase}
.el-section-title{text-align:center;font-size:1.7rem;font-weight:700;margin-bottom:8px}
.el-section-sub{text-align:center;color:var(--text-m);margin-bottom:36px;max-width:560px;margin-left:auto;margin-right:auto}

/* Node grid */
.el-nodes{display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:16px;margin-bottom:48px}
.el-node{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:24px;transition:border-color .2s,transform .18s;position:relative;overflow:hidden}
.el-node::before{content:'';position:absolute;top:0;left:0;width:3px;height:100%;background:var(--accent)}
.el-node:hover{border-color:var(--accent);transform:translateY(-2px)}
.el-node-id{font-family:var(--mono);font-size:0.72rem;color:var(--accent2);margin-bottom:6px;letter-spacing:0.05em}
.el-node h3{font-size:1rem;font-weight:600;margin-bottom:8px;line-height:1.3}
.el-node p{font-size:0.85rem;color:var(--text-m);line-height:1.5}
.el-node a{position:absolute;inset:0;display:block}

/* Reference table */
.el-ref-table-wrap{overflow-x:auto;margin:24px 0}
.el-ref-table{width:100%;border-collapse:collapse;font-size:0.87rem}
.el-ref-table thead{background:var(--surface2)}
.el-ref-table th{padding:10px 14px;text-align:left;font-weight:600;border-bottom:2px solid var(--border);color:var(--text-m);white-space:nowrap}
.el-ref-table td{padding:9px 14px;border-bottom:1px solid var(--border);vertical-align:top}
.el-ref-table tr:last-child td{border-bottom:none}
.el-ref-table tr:hover td{background:var(--surface2)}
.tag-mth{background:rgba(124,58,237,0.15);color:var(--accent2);border-radius:3px;padding:1px 7px;font-size:0.77rem;font-family:var(--mono)}
.tag-arch{background:rgba(74,222,128,0.12);color:var(--green);border-radius:3px;padding:1px 7px;font-size:0.77rem;font-family:var(--mono)}

/* Article layout */
.el-article-wrap{padding:48px 0}
.el-article-grid{display:grid;grid-template-columns:1fr 280px;gap:40px;align-items:start}
.el-article h1{font-size:clamp(1.5rem,3vw,2.2rem);margin-bottom:12px;font-weight:700}
.el-article .lead{font-size:1.08rem;color:var(--text-m);margin-bottom:28px;border-left:3px solid var(--accent);padding-left:14px}
.el-article h2{font-size:1.25rem;font-weight:700;margin:32px 0 10px;padding-top:32px;border-top:1px solid var(--border)}
.el-article h3{font-size:1rem;font-weight:600;margin:20px 0 8px;color:var(--accent2)}
.el-article p{margin-bottom:14px}
.el-article ul,.el-article ol{margin-bottom:14px}
.el-article li{margin-bottom:6px}
.el-code{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:16px;font-family:var(--mono);font-size:0.83rem;overflow-x:auto;margin:16px 0;color:#a78bfa}
.el-formula{background:var(--surface2);border-left:3px solid var(--accent);padding:12px 16px;border-radius:0 var(--radius) var(--radius) 0;font-family:var(--mono);font-size:0.9rem;margin:16px 0}
.el-note{background:rgba(124,58,237,0.08);border:1px solid rgba(124,58,237,0.25);border-radius:var(--radius);padding:14px 18px;margin:20px 0;font-size:0.9rem}
.el-note strong{color:var(--accent2)}

details{border:1px solid var(--border);border-radius:var(--radius);margin:12px 0}
details summary{padding:12px 16px;cursor:pointer;font-weight:600;font-size:0.9rem;list-style:none;display:flex;align-items:center;justify-content:space-between;color:var(--text)}
details summary::after{content:'▾';font-size:0.8rem;color:var(--text-sm);transition:transform .2s}
details[open] summary::after{transform:rotate(-180deg)}
details>div{padding:12px 16px 16px;font-size:0.9rem;color:var(--text-m);border-top:1px solid var(--border)}

/* Sidebar */
.el-sidebar-box{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:20px;margin-bottom:16px}
.el-sidebar-box .el-sbl{font-family:var(--mono);font-size:0.72rem;text-transform:uppercase;letter-spacing:0.09em;color:var(--accent2);margin-bottom:12px}
.el-sidebar-box ul{list-style:none;padding:0}
.el-sidebar-box li{border-bottom:1px solid var(--border);padding:6px 0;font-size:0.87rem}
.el-sidebar-box li:last-child{border-bottom:none}
.el-sidebar-box a{color:var(--text-m)}
.el-sidebar-box a:hover{color:var(--text)}

/* Stats strip */
.el-stats{background:var(--surface);border-top:1px solid var(--border);border-bottom:1px solid var(--border);padding:28px 0}
.el-stats-row{display:flex;gap:32px;justify-content:center;flex-wrap:wrap}
.el-stat{text-align:center}
.el-stat-num{font-size:1.8rem;font-weight:800;color:var(--accent2);font-family:var(--mono);display:block;line-height:1.1}
.el-stat-label{font-size:0.78rem;color:var(--text-sm);text-transform:uppercase;letter-spacing:0.06em}

/* Related */
.el-related{background:var(--surface2);border-top:1px solid var(--border);padding:48px 0}
.el-related h2{text-align:center;font-size:1.2rem;margin-bottom:24px;color:var(--text-m)}
.el-related-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(210px,1fr));gap:12px}
.el-rc{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:16px 18px;display:block;transition:border-color .2s}
.el-rc:hover{border-color:var(--accent)}
.el-rc-label{display:block;font-size:0.87rem;font-weight:600;color:var(--text);margin-bottom:4px}
.el-rc-desc{display:block;font-size:0.78rem;color:var(--text-sm)}

/* Footer */
.el-footer{background:var(--surface2);border-top:1px solid var(--border);padding:40px 0 0}
.el-footer-grid{display:grid;grid-template-columns:2fr 1fr;gap:40px;margin-bottom:32px}
.el-footer-desc{color:var(--text-m);font-size:0.85rem;margin-top:10px;max-width:340px}
.el-footer h3{font-size:0.8rem;text-transform:uppercase;letter-spacing:0.08em;color:var(--text-sm);margin-bottom:12px}
.el-footer ul{list-style:none;padding:0}
.el-footer li{margin-bottom:7px;font-size:0.87rem}
.el-footer-bar{background:var(--surface);border-top:1px solid var(--border);padding:12px 0;font-size:0.8rem;color:var(--text-sm)}

/* Responsive */
@media(max-width:900px){
  .el-hero-inner{grid-template-columns:1fr}
  .el-hero-img{display:none}
  .el-article-grid{grid-template-columns:1fr}
  .el-footer-grid{grid-template-columns:1fr}
}
@media(max-width:680px){
  .el-toggle{display:block}
  .el-nav{display:none;position:absolute;top:100%;left:0;right:0;background:var(--surface);border-bottom:1px solid var(--border);padding:12px 0}
  .el-nav.open{display:block}
  .el-nav ul{flex-direction:column;gap:2px;padding:0 16px}
  .el-header-row{flex-wrap:wrap;position:relative}
  .el-header{position:sticky;top:0}
}