/* Project Myelin — dark neuro theme */
:root{
  --bg:#0a0e1a; --bg2:#0f1424; --panel:#141a2e; --panel2:#1a2138;
  --line:#232b45; --line2:#2e385c;
  --txt:#e7ecf7; --mut:#9aa6c4; --dim:#6b7699;
  --accent:#5b8cff; --accent2:#a06bff; --glow:#4de0ff;
  --cloze:#ffd24d; --cloze-bg:rgba(255,210,77,.12);
  --radius:16px; --sb:290px;
  --grad:linear-gradient(135deg,#5b8cff 0%,#a06bff 60%,#4de0ff 120%);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0; background:var(--bg); color:var(--txt);
  font:15.5px/1.65 -apple-system,BlinkMacSystemFont,"Segoe UI",Inter,system-ui,sans-serif;
  -webkit-font-smoothing:antialiased;
}
body{background:
  radial-gradient(900px 500px at 15% -10%,rgba(91,140,255,.10),transparent 60%),
  radial-gradient(800px 500px at 110% 10%,rgba(160,107,255,.10),transparent 55%),
  var(--bg);
  background-attachment:fixed;
}
a{color:inherit;text-decoration:none}
img{max-width:100%;height:auto;border-radius:10px;display:block}

/* ---------- sidebar ---------- */
.sidebar{
  position:fixed;top:0;left:0;width:var(--sb);height:100vh;overflow-y:auto;
  background:linear-gradient(180deg,var(--bg2),#0b1020);
  border-right:1px solid var(--line);padding:18px 14px 40px;z-index:40;
}
.sidebar::-webkit-scrollbar{width:8px}
.sidebar::-webkit-scrollbar-thumb{background:var(--line2);border-radius:8px}
.brand{display:flex;align-items:center;gap:10px;font-weight:800;letter-spacing:.5px;
  font-size:15px;padding:8px 10px 16px;color:#fff}
.brand .bolt{font-size:20px;filter:drop-shadow(0 0 10px rgba(77,224,255,.5))}
.nav-group{margin-bottom:4px}
.nav-node{width:100%;display:flex;align-items:center;gap:10px;background:none;border:0;
  color:var(--txt);font:inherit;font-weight:650;cursor:pointer;padding:11px 12px;border-radius:11px;
  text-align:left}
.nav-node:hover{background:var(--panel)}
.nav-node .ico{font-size:16px}
.nav-node .chev{margin-left:auto;transition:transform .2s;color:var(--dim)}
.nav-group.open .nav-node .chev{transform:rotate(90deg)}
.nav-subs{display:none;flex-direction:column;padding:2px 0 6px 6px;margin-left:14px;
  border-left:1px solid var(--line)}
.nav-group.open .nav-subs{display:flex}
.nav-sub{display:flex;align-items:center;gap:8px;color:var(--mut);font-size:13.5px;
  padding:7px 12px;border-radius:9px;margin:1px 0}
.nav-sub:hover{background:var(--panel);color:var(--txt)}
.nav-sub.active{background:var(--panel2);color:#fff;box-shadow:inset 3px 0 0 var(--accent)}
.nav-sub.overview{color:var(--dim);font-style:italic}
.nav-sub .cnt{margin-left:auto;font-size:11px;color:var(--dim);background:var(--panel);
  padding:1px 7px;border-radius:20px}

/* ---------- main ---------- */
.content{margin-left:var(--sb);padding:0 clamp(16px,4vw,54px) 60px;max-width:1150px}
.topbar{position:sticky;top:0;z-index:20;display:flex;align-items:center;gap:16px;
  padding:16px 0 14px;margin-bottom:14px;
  background:linear-gradient(180deg,var(--bg) 55%,transparent);
  backdrop-filter:blur(4px)}
.crumb{color:var(--mut);font-size:14px;font-weight:600}
.cloze-toggle{margin-left:auto;background:var(--panel);border:1px solid var(--line2);
  color:var(--txt);font:inherit;font-weight:600;font-size:13px;padding:8px 16px;border-radius:20px;
  cursor:pointer;transition:.15s}
.cloze-toggle:hover{border-color:var(--accent);color:#fff}
.cloze-toggle.hiding{background:var(--grad);border-color:transparent;color:#0a0e1a}

.page-head{padding:10px 0 22px;border-bottom:1px solid var(--line);margin-bottom:26px}
.page-head h1{margin:0;font-size:clamp(26px,4vw,38px);letter-spacing:-.5px;
  background:var(--grad);-webkit-background-clip:text;background-clip:text;color:transparent}
.page-head .sub{margin:8px 0 0;color:var(--mut);font-size:14px}
.hero-node{text-align:center;border:0}
.hero-node .big-emoji{font-size:56px;filter:drop-shadow(0 0 24px rgba(91,140,255,.45))}

/* ---------- notes ---------- */
.notes{display:flex;flex-direction:column;gap:18px}
.note{background:linear-gradient(180deg,var(--panel),var(--bg2));
  border:1px solid var(--line);border-radius:var(--radius);padding:20px 22px;
  box-shadow:0 2px 20px rgba(0,0,0,.25)}
.note:hover{border-color:var(--line2)}
.note .body>div{margin:2px 0}
.note b,.note strong{color:#fff}
.note ul,.note ol{margin:8px 0;padding-left:22px}
.note li{margin:4px 0}
.note img{margin:12px auto;border:1px solid var(--line2);background:#fff}
.extra{margin-top:14px;padding-top:12px;border-top:1px dashed var(--line2);color:var(--mut);font-size:14px}

/* cloze */
.cloze{border-radius:5px;padding:0 3px;font-weight:600}
.cz-a{color:var(--cloze);background:var(--cloze-bg);border-radius:5px;padding:0 3px}
.cz-h{display:none;color:var(--accent);font-style:italic}
body.hide-cloze .cz-a{display:none}
body.hide-cloze .cz-h{display:inline;background:var(--cloze-bg);border-radius:5px;padding:0 8px;
  border-bottom:2px solid var(--cloze)}

/* image occlusion figures */
.io-card{margin:0;background:linear-gradient(180deg,var(--panel),var(--bg2));
  border:1px solid var(--line);border-radius:var(--radius);padding:16px;text-align:center}
.io-card img{margin:0 auto;background:#fff;border-radius:10px}
.io-card figcaption{margin-top:12px;color:var(--mut);font-size:13.5px}

/* ---------- node overview tiles ---------- */
.tiles{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:16px}
.tile{background:linear-gradient(180deg,var(--panel),var(--bg2));border:1px solid var(--line);
  border-radius:14px;padding:20px 18px;transition:.18s}
.tile:hover{transform:translateY(-3px);border-color:var(--accent);
  box-shadow:0 10px 30px rgba(91,140,255,.18)}
.tile h3{margin:0 0 6px;font-size:17px;color:#fff}
.tile p{margin:0;color:var(--mut);font-size:13px}

/* ---------- landing ---------- */
.hero{text-align:center;padding:70px 10px 40px}
.hero-bolt{font-size:70px;filter:drop-shadow(0 0 30px rgba(77,224,255,.5))}
.hero h1{font-size:clamp(40px,8vw,74px);margin:10px 0 4px;letter-spacing:-2px;
  background:var(--grad);-webkit-background-clip:text;background-clip:text;color:transparent}
.hero .tagline{color:var(--mut);font-size:clamp(15px,2.4vw,19px);max-width:620px;margin:8px auto 0}
.hero .stat{color:var(--dim);font-size:14px;margin-top:18px;letter-spacing:.5px}
.node-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(250px,1fr));gap:22px;
  margin-top:30px}
.node-card{position:relative;background:linear-gradient(180deg,var(--panel),var(--bg2));
  border:1px solid var(--line);border-radius:20px;padding:32px 26px;overflow:hidden;transition:.2s}
.node-card::before{content:"";position:absolute;inset:0;opacity:0;background:var(--grad);
  transition:.2s;z-index:0}
.node-card:hover{transform:translateY(-5px);border-color:transparent;
  box-shadow:0 16px 44px rgba(120,110,255,.28)}
.node-card>*{position:relative;z-index:1}
.nc-emoji{font-size:42px}
.nc-num{color:var(--dim);font-size:12px;letter-spacing:2px;margin-top:10px;font-weight:700}
.node-card h2{margin:6px 0 6px;font-size:26px;color:#fff}
.node-card p{margin:0;color:var(--mut);font-size:14px}
.nc-go{display:inline-block;margin-top:16px;color:var(--glow);font-weight:600;font-size:14px}

.foot{margin-top:50px;padding-top:20px;border-top:1px solid var(--line);
  color:var(--dim);font-size:12.5px;text-align:center}

/* ---------- mobile ---------- */
.menu-btn,.scrim{display:none}
@media(max-width:900px){
  .content{margin-left:0;padding-top:8px}
  .sidebar{transform:translateX(-100%);transition:transform .25s;box-shadow:0 0 40px rgba(0,0,0,.6)}
  body.nav-open .sidebar{transform:none}
  .menu-btn{display:flex;align-items:center;justify-content:center;position:fixed;top:14px;left:14px;
    z-index:50;width:44px;height:44px;border-radius:12px;border:1px solid var(--line2);
    background:var(--panel);color:#fff;font-size:20px;cursor:pointer}
  body.nav-open .scrim{display:block;position:fixed;inset:0;background:rgba(0,0,0,.5);z-index:35}
  .topbar{padding-left:54px}
}