:root{
  --bg:#fbfcfe; --surface:#ffffff; --surface-2:#f4f7fb; --border:#e3e9f2;
  --ink:#16202e; --ink-soft:#4b5a70;
  --indigo:#4f46e5; --teal:#0d9488; --amber:#d97706; --rose:#e11d48; --sky:#0369a1;
  --grad:linear-gradient(135deg,#6366f1 0%,#0ea5e9 50%,#14b8a6 100%);
  --radius:16px;
  --shadow:0 1px 2px rgba(16,32,56,.06),0 8px 24px rgba(16,32,56,.08);
  --font:"Inter","Segoe UI",system-ui,sans-serif;
  --serif:"Source Serif 4",Georgia,serif;
  --mono:"JetBrains Mono","Cascadia Code",Consolas,monospace;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:76px}
body{margin:0;background:var(--bg);color:var(--ink);font:16.5px/1.7 var(--font)}
a{color:var(--sky);text-decoration:none}
a:hover{text-decoration:underline}
.wrap{max-width:1080px;margin:0 auto;padding:0 20px}
img{max-width:100%;height:auto}

/* top bar */
.topbar{position:sticky;top:0;z-index:20;background:rgba(255,255,255,.86);
  backdrop-filter:blur(10px);border-bottom:1px solid var(--border)}
.topbar .wrap{display:flex;align-items:center;justify-content:space-between;gap:16px;min-height:60px}
.brand{font-weight:800;font-size:1.15rem;color:var(--indigo);letter-spacing:-.01em}
.nav{display:flex;flex-wrap:wrap;gap:4px 18px;font-size:.93rem}
.nav a{color:var(--ink-soft);font-weight:500}
.nav a:hover{color:var(--indigo);text-decoration:none}

/* hero */
.hero{background:var(--grad);color:#fff;padding:72px 0 64px}
.hero h1{font-size:clamp(2.4rem,6vw,3.6rem);margin:0 0 10px;letter-spacing:-.03em;line-height:1.1}
.hero p.pitch{font-size:clamp(1.05rem,2.4vw,1.3rem);max-width:760px;margin:0 0 12px;opacity:.97}
.hero p.cite{font-size:.95rem;opacity:.92;margin:0 0 26px;max-width:760px}
.hero p.cite a{color:#fff;text-decoration:underline}
.pills{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:22px}
.pill{background:rgba(255,255,255,.2);border:1px solid rgba(255,255,255,.4);border-radius:999px;
  padding:3px 13px;font-size:.84rem;font-weight:600}
.install{display:flex;align-items:center;gap:10px;background:rgba(15,23,42,.28);
  border:1px solid rgba(255,255,255,.35);border-radius:12px;padding:10px 14px;max-width:420px;
  font-family:var(--mono);font-size:1rem}
.install code{flex:1;color:#fff;background:none;padding:0;overflow-x:auto;white-space:nowrap}
.btns{display:flex;flex-wrap:wrap;gap:12px;margin-top:24px}
.btn{display:inline-block;padding:11px 22px;border-radius:12px;font-weight:700;font-size:.97rem;
  background:#fff;color:var(--indigo);box-shadow:var(--shadow)}
.btn.ghost{background:transparent;color:#fff;border:1.5px solid rgba(255,255,255,.75);box-shadow:none}
.btn:hover{text-decoration:none;transform:translateY(-1px)}

/* sections */
section{padding:60px 0 8px}
.eyebrow{display:inline-block;font-size:.78rem;font-weight:800;letter-spacing:.09em;
  text-transform:uppercase;margin-bottom:6px}
.e-indigo{color:var(--indigo)} .e-teal{color:var(--teal)} .e-amber{color:var(--amber)}
.e-rose{color:var(--rose)} .e-sky{color:var(--sky)}
h2{font-size:clamp(1.6rem,3.6vw,2.1rem);margin:0 0 16px;letter-spacing:-.02em;line-height:1.2}
h3{font-size:1.18rem;margin:28px 0 10px}
p,li{max-width:74ch}
.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);
  box-shadow:var(--shadow);padding:26px;margin:18px 0;border-top:4px solid var(--indigo)}
.card.teal{border-top-color:var(--teal)} .card.amber{border-top-color:var(--amber)}
.card.rose{border-top-color:var(--rose)} .card.sky{border-top-color:var(--sky)}
.card > :first-child{margin-top:0} .card > :last-child{margin-bottom:0}
.grid{display:grid;gap:18px;grid-template-columns:repeat(auto-fit,minmax(225px,1fr))}
.grid .card{margin:0}
.grid .card h3{margin-top:0}
.two{display:grid;gap:18px;grid-template-columns:repeat(auto-fit,minmax(300px,1fr))}
.theory{font-family:var(--serif);font-size:1.06rem}
.theory h3{font-family:var(--font)}

/* code */
pre{background:var(--surface-2);border:1px solid var(--border);border-radius:12px;
  padding:16px 18px;overflow-x:auto;font:14.2px/1.6 var(--mono);position:relative;margin:14px 0}
pre code.hljs{background:transparent;padding:0}
code{font-family:var(--mono);font-size:.9em;background:var(--surface-2);padding:2px 6px;border-radius:6px}
pre code{background:none;padding:0;font-size:inherit}
.copy{position:absolute;top:8px;right:8px;border:1px solid var(--border);background:#fff;
  color:var(--ink-soft);border-radius:8px;font:600 12px var(--font);padding:4px 10px;cursor:pointer}
.copy:hover{color:var(--indigo);border-color:var(--indigo)}
.install .copy{position:static;background:rgba(255,255,255,.92)}

/* tables */
.tablewrap{overflow-x:auto;margin:14px 0;border:1px solid var(--border);border-radius:12px;background:#fff}
table{border-collapse:collapse;width:100%;font-size:.94rem}
th,td{padding:9px 13px;text-align:left;border-bottom:1px solid var(--border);vertical-align:top}
thead th{background:var(--surface-2);font-weight:700;position:sticky;top:0}
tbody tr:nth-child(even){background:rgba(244,247,251,.55)}
tbody tr:last-child td{border-bottom:none}
td.num,th.num{text-align:right;font-family:var(--mono);font-size:.88rem;white-space:nowrap}
tr.sect td{background:var(--surface-2);font-style:italic;font-weight:600}
caption{caption-side:top;text-align:left;font-weight:700;padding:10px 13px}

/* callouts & figures */
.note{border-left:4px solid var(--amber);background:rgba(217,119,6,.08);border-radius:0 12px 12px 0;
  padding:13px 17px;margin:16px 0}
.warn{border-left:4px solid var(--rose);background:rgba(225,29,72,.07);border-radius:0 12px 12px 0;
  padding:13px 17px;margin:16px 0}
.note p,.warn p{margin:0}
figure{margin:18px 0;background:#fff;border:1px solid var(--border);border-radius:var(--radius);
  box-shadow:var(--shadow);padding:14px}
figure img{display:block;margin:0 auto;border-radius:8px}
figcaption{color:var(--ink-soft);font-size:.92rem;margin-top:8px;text-align:center}
.figs{display:grid;gap:18px;grid-template-columns:repeat(auto-fit,minmax(310px,1fr))}
.figs figure{margin:0}

/* author & footer */
.author{display:grid;gap:18px;grid-template-columns:repeat(auto-fit,minmax(280px,1fr))}
.links{list-style:none;padding:0;margin:0}
.links li{padding:4px 0}
footer{margin-top:60px;border-top:1px solid var(--border);padding:26px 0;color:var(--ink-soft);
  font-size:.92rem;text-align:center}
.katex-display{overflow-x:auto;overflow-y:hidden;padding:4px 0}

@media (max-width:720px){
  .nav{display:none}
  .hero{padding:48px 0 44px}
  section{padding-top:44px}
  .card{padding:20px}
}
@media print{
  .topbar,.copy,.btns{display:none}
  .hero{background:none;color:#000;padding:20px 0}
  .card,figure{box-shadow:none}
}