/* ---------- Design tokens ---------- */
:root{
  --accent-1:#7c3aed;          /* violet */
  --accent-2:#06b6d4;          /* cyan   */
  --accent-grad:linear-gradient(120deg,#7c3aed 0%,#6366f1 45%,#06b6d4 100%);
  --radius:14px;
  --radius-sm:9px;
  --maxw:1080px;
  --font:'Inter',-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Helvetica,Arial,sans-serif;
  --mono:'JetBrains Mono',ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  --topbar-h:60px;
  --side-w:264px;
  --transition:.22s cubic-bezier(.4,0,.2,1);
}
:root[data-theme="light"]{
  --bg:#f7f8fb;
  --bg-elev:#ffffff;
  --bg-soft:#f1f2f8;
  --text:#1c2230;
  --text-soft:#5a6478;
  --muted:#7c8499;
  --border:#e4e7ef;
  --border-strong:#d2d7e3;
  --code-bg:#f4f5fb;
  --code-text:#3a2a6d;
  --shadow:0 1px 2px rgba(20,24,40,.06),0 8px 24px rgba(20,24,40,.06);
  --shadow-sm:0 1px 2px rgba(20,24,40,.07);
  --side-bg:#ffffff;
  --table-stripe:#f7f8fc;
}
:root[data-theme="dark"]{
  --bg:#0d1018;
  --bg-elev:#161a26;
  --bg-soft:#1b2030;
  --text:#e6e9f2;
  --text-soft:#a8b0c5;
  --muted:#7f879d;
  --border:#262c3c;
  --border-strong:#333b50;
  --code-bg:#121622;
  --code-text:#c7b8ff;
  --shadow:0 1px 2px rgba(0,0,0,.4),0 12px 32px rgba(0,0,0,.4);
  --shadow-sm:0 1px 2px rgba(0,0,0,.4);
  --side-bg:#11151f;
  --table-stripe:#171c29;
}

*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:calc(var(--topbar-h) + 16px)}
body{
  margin:0;font-family:var(--font);background:var(--bg);color:var(--text);
  line-height:1.65;-webkit-font-smoothing:antialiased;
}
a{color:var(--accent-1);text-decoration:none}
:root[data-theme="dark"] a{color:#a78bfa}
a:hover{text-decoration:underline}

.skip-link{position:absolute;left:-999px;top:0;background:var(--accent-1);color:#fff;
  padding:10px 16px;border-radius:0 0 8px 0;z-index:200}
.skip-link:focus{left:0}

/* ---------- Top bar ---------- */
.topbar{
  position:sticky;top:0;z-index:100;height:var(--topbar-h);
  display:flex;align-items:center;gap:12px;padding:0 16px;
  background:color-mix(in srgb,var(--bg-elev) 88%,transparent);
  backdrop-filter:saturate(150%) blur(10px);
  border-bottom:1px solid var(--border);
}
.brand{display:flex;align-items:baseline;gap:8px;color:var(--text)}
.brand:hover{text-decoration:none}
.brand-eye{width:18px;height:18px;border-radius:50%;background:var(--accent-grad);
  position:relative;align-self:center;box-shadow:0 0 0 3px color-mix(in srgb,var(--accent-1) 22%,transparent)}
.brand-eye::after{content:"";position:absolute;inset:6px;border-radius:50%;background:var(--bg-elev)}
.brand-name{font-weight:800;font-size:1.18rem;letter-spacing:-.02em;
  background:var(--accent-grad);-webkit-background-clip:text;background-clip:text;color:transparent}
.brand-sub{font-size:.78rem;color:var(--muted);font-weight:500}
@media(max-width:640px){.brand-sub{display:none}}
.topbar-spacer{flex:1}
.topbar-link{display:flex;align-items:center;color:var(--text-soft);padding:8px;border-radius:8px}
.topbar-link:hover{color:var(--text);background:var(--bg-soft)}

.icon-btn{
  display:inline-flex;align-items:center;justify-content:center;
  width:38px;height:38px;border:1px solid var(--border);border-radius:10px;
  background:var(--bg-elev);color:var(--text-soft);cursor:pointer;transition:var(--transition);
}
.icon-btn:hover{color:var(--text);border-color:var(--border-strong);background:var(--bg-soft)}
.hamburger{display:none}
@media(max-width:980px){.hamburger{display:inline-flex}}

/* theme toggle icon swap */
.ico-moon{display:none}
:root[data-theme="dark"] .ico-sun{display:none}
:root[data-theme="dark"] .ico-moon{display:inline}

/* ---------- Layout ---------- */
.layout{display:flex;align-items:flex-start;max-width:1320px;margin:0 auto}
.sidebar{
  position:sticky;top:var(--topbar-h);align-self:flex-start;
  width:var(--side-w);height:calc(100vh - var(--topbar-h));overflow-y:auto;
  background:var(--side-bg);border-right:1px solid var(--border);
  padding:18px 12px 40px;flex:none;transition:transform var(--transition);
}
.content{flex:1;min-width:0;max-width:var(--maxw);margin:0 auto;padding:28px 28px 60px;width:100%}

/* sidebar collapsed (desktop) */
body.sidebar-collapsed .sidebar{display:none}

/* ---------- Sidebar nav ---------- */
.nav-group{margin-bottom:18px}
.nav-group-title{font-size:.72rem;text-transform:uppercase;letter-spacing:.09em;
  color:var(--muted);font-weight:700;padding:0 12px 6px}
.side-nav ul{list-style:none;margin:0;padding:0}
.side-nav a{
  display:block;padding:8px 12px;border-radius:9px;color:var(--text-soft);
  font-size:.93rem;font-weight:500;transition:var(--transition);
}
.side-nav a:hover{background:var(--bg-soft);color:var(--text);text-decoration:none}
.side-nav a.active{
  color:#fff;background:var(--accent-grad);
  box-shadow:0 4px 12px color-mix(in srgb,var(--accent-1) 35%,transparent);
}
:root[data-theme="dark"] .side-nav a.active{color:#fff}

/* ---------- backdrop (mobile) ---------- */
.backdrop{position:fixed;inset:var(--topbar-h) 0 0 0;background:rgba(8,10,18,.5);
  z-index:80;backdrop-filter:blur(2px)}

@media(max-width:980px){
  .sidebar{
    position:fixed;top:var(--topbar-h);left:0;z-index:90;
    height:calc(100vh - var(--topbar-h));box-shadow:var(--shadow);
    transform:translateX(-105%);display:block;
  }
  body.sidebar-open .sidebar{transform:translateX(0)}
  body.sidebar-collapsed .sidebar{display:block}  /* class is desktop-only meaning */
  .content{max-width:100%;padding:20px 16px 50px}
}

/* ---------- Prose ---------- */
.breadcrumb{font-size:.82rem;color:var(--muted);margin-bottom:10px}
.breadcrumb a{color:var(--text-soft)}
.breadcrumb .sep{opacity:.5;margin:0 6px}
.breadcrumb .crumb-cur{color:var(--text)}

.page-head{display:flex;align-items:center;justify-content:space-between;gap:16px;
  flex-wrap:wrap;border-bottom:1px solid var(--border);padding-bottom:16px;margin-bottom:8px}
.page-head h1{margin:0;font-size:2rem;letter-spacing:-.02em;line-height:1.2}
.md-link{display:inline-flex;align-items:center;gap:7px;font-size:.85rem;font-weight:600;
  padding:8px 13px;border:1px solid var(--border-strong);border-radius:10px;
  background:var(--bg-elev);color:var(--text-soft);white-space:nowrap}
.md-link:hover{color:var(--text);border-color:var(--accent-1);text-decoration:none;
  box-shadow:var(--shadow-sm)}

.on-this-page{float:right;width:220px;margin:6px 0 18px 24px;padding:14px 16px;
  background:var(--bg-elev);border:1px solid var(--border);border-radius:var(--radius)}
.on-this-page .otp-title{font-size:.74rem;text-transform:uppercase;letter-spacing:.08em;
  color:var(--muted);font-weight:700;margin-bottom:8px}
.on-this-page ul{list-style:none;margin:0;padding:0}
.on-this-page a{display:block;padding:4px 0;font-size:.85rem;color:var(--text-soft)}
.on-this-page a:hover{color:var(--accent-1)}
@media(max-width:760px){.on-this-page{float:none;width:auto;margin:0 0 20px}}

.prose h2{font-size:1.5rem;margin:2.2rem 0 .8rem;letter-spacing:-.01em;
  padding-top:.4rem;scroll-margin-top:calc(var(--topbar-h) + 12px)}
.prose h3{font-size:1.18rem;margin:1.8rem 0 .6rem}
.prose p{margin:.7rem 0;color:var(--text)}
.prose ul,.prose ol{padding-left:1.4rem}
.prose li{margin:.35rem 0}
.prose strong{color:var(--text);font-weight:700}
.prose code{font-family:var(--mono);font-size:.86em;background:var(--code-bg);
  color:var(--code-text);padding:.12em .42em;border-radius:6px;
  border:1px solid var(--border)}
.prose pre{background:var(--code-bg);border:1px solid var(--border);border-radius:var(--radius);
  padding:16px 18px;overflow:auto;position:relative;margin:1.1rem 0}
.prose pre code{background:none;border:none;padding:0;color:var(--text);font-size:.85rem;line-height:1.6}
hr{border:none;border-top:1px solid var(--border);margin:2rem 0}

/* copy button */
.copy-btn{position:absolute;top:8px;right:8px;font-size:.72rem;font-weight:600;
  padding:5px 10px;border:1px solid var(--border-strong);border-radius:8px;
  background:var(--bg-elev);color:var(--text-soft);cursor:pointer;opacity:0;transition:var(--transition)}
.prose pre:hover .copy-btn{opacity:1}
.copy-btn:hover{color:var(--text);border-color:var(--accent-1)}
.copy-btn.copied{color:#fff;background:var(--accent-1);border-color:var(--accent-1)}

/* ---------- Tables ---------- */
.table-wrap{overflow-x:auto;margin:1.1rem 0;border:1px solid var(--border);border-radius:var(--radius)}
table{border-collapse:collapse;width:100%;font-size:.9rem;min-width:520px}
th,td{text-align:left;padding:10px 14px;border-bottom:1px solid var(--border);vertical-align:top}
thead th{background:var(--bg-soft);font-weight:700;color:var(--text);white-space:nowrap;
  position:sticky;top:0}
tbody tr:nth-child(even){background:var(--table-stripe)}
tbody tr:last-child td{border-bottom:none}
td code{white-space:nowrap}

/* ---------- Cards ---------- */
.card-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:16px;margin:1.4rem 0}
.card{background:var(--bg-elev);border:1px solid var(--border);border-radius:var(--radius);
  padding:20px;box-shadow:var(--shadow-sm);transition:var(--transition)}
.card:hover{transform:translateY(-3px);box-shadow:var(--shadow);border-color:var(--border-strong)}
.card h3{margin:.2rem 0 .5rem;font-size:1.08rem}
.card p{margin:0;color:var(--text-soft);font-size:.92rem}
.card a{font-weight:600}
.card .card-ico{width:40px;height:40px;border-radius:11px;display:flex;align-items:center;
  justify-content:center;background:var(--accent-grad);color:#fff;margin-bottom:12px;font-size:1.2rem}

/* ---------- Badges / callouts ---------- */
.badge{display:inline-block;font-size:.74rem;font-weight:700;padding:2px 9px;border-radius:999px;
  background:color-mix(in srgb,var(--accent-1) 14%,transparent);color:var(--accent-1);
  border:1px solid color-mix(in srgb,var(--accent-1) 30%,transparent)}
:root[data-theme="dark"] .badge{color:#c4b5fd}
.badge.green{background:#10b98122;color:#059669;border-color:#10b98155}
.badge.amber{background:#f59e0b22;color:#b45309;border-color:#f59e0b55}
.badge.red{background:#ef444422;color:#dc2626;border-color:#ef444455}
.badge.gray{background:var(--bg-soft);color:var(--muted);border-color:var(--border)}
:root[data-theme="dark"] .badge.green{color:#34d399}
:root[data-theme="dark"] .badge.amber{color:#fbbf24}
:root[data-theme="dark"] .badge.red{color:#f87171}

.callout{display:flex;gap:12px;padding:14px 16px;border-radius:var(--radius);margin:1.2rem 0;
  border:1px solid var(--border);background:var(--bg-elev)}
.callout .ico{font-size:1.15rem;line-height:1.5}
.callout.tip{border-left:4px solid var(--accent-2);background:color-mix(in srgb,var(--accent-2) 7%,var(--bg-elev))}
.callout.note{border-left:4px solid var(--accent-1);background:color-mix(in srgb,var(--accent-1) 7%,var(--bg-elev))}
.callout.warn{border-left:4px solid #f59e0b;background:#f59e0b12}
.callout p{margin:.2rem 0}
.callout strong{display:block;margin-bottom:2px}

/* ---------- Hero (home) ---------- */
.hero{position:relative;overflow:hidden;border-radius:24px;padding:54px 40px;margin:6px 0 30px;
  background:var(--accent-grad);color:#fff;box-shadow:0 20px 50px color-mix(in srgb,var(--accent-1) 35%,transparent)}
.hero::after{content:"";position:absolute;inset:0;
  background:radial-gradient(circle at 80% 20%,rgba(255,255,255,.25),transparent 45%),
             radial-gradient(circle at 15% 90%,rgba(255,255,255,.15),transparent 40%);pointer-events:none}
.hero-eyes{position:absolute;right:34px;top:34px;display:grid;grid-template-columns:repeat(3,1fr);
  gap:9px;opacity:.5}
.hero-eyes span{width:13px;height:13px;border-radius:50%;background:rgba(255,255,255,.6);
  box-shadow:inset 0 0 0 3px rgba(255,255,255,.3)}
@media(max-width:640px){.hero-eyes{display:none}}
.hero h1{font-size:2.6rem;margin:0 0 6px;letter-spacing:-.03em;line-height:1.1;color:#fff}
.hero .tagline{font-size:1.25rem;font-weight:600;margin:0 0 10px;color:#fff}
.hero p{font-size:1.02rem;max-width:60ch;color:rgba(255,255,255,.92);position:relative}
.hero .cta-row{display:flex;gap:12px;flex-wrap:wrap;margin-top:22px;position:relative}
.btn{display:inline-flex;align-items:center;gap:8px;font-weight:700;font-size:.95rem;
  padding:12px 22px;border-radius:12px;transition:var(--transition);cursor:pointer;border:1px solid transparent}
.btn-primary{background:#fff;color:var(--accent-1)}
.btn-primary:hover{text-decoration:none;transform:translateY(-2px);box-shadow:0 10px 24px rgba(0,0,0,.18)}
.btn-ghost{background:rgba(255,255,255,.14);color:#fff;border-color:rgba(255,255,255,.4)}
.btn-ghost:hover{text-decoration:none;background:rgba(255,255,255,.24)}
@media(max-width:640px){.hero{padding:36px 24px}.hero h1{font-size:2rem}}

.stat-row{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:14px;margin:1.4rem 0}
.stat{background:var(--bg-elev);border:1px solid var(--border);border-radius:var(--radius);
  padding:18px;text-align:center}
.stat .num{font-size:1.8rem;font-weight:800;
  background:var(--accent-grad);-webkit-background-clip:text;background-clip:text;color:transparent}
.stat .lbl{font-size:.82rem;color:var(--muted);font-weight:600}

/* ---------- Mermaid + chart ---------- */
.mermaid{background:var(--bg-elev);border:1px solid var(--border);border-radius:var(--radius);
  padding:18px;margin:1.2rem 0;text-align:center;overflow-x:auto}
.chart-wrap{background:var(--bg-elev);border:1px solid var(--border);border-radius:var(--radius);
  padding:18px;margin:1.2rem 0}

.page-footer{margin-top:48px;padding-top:22px;border-top:1px solid var(--border);
  font-size:.86rem;color:var(--text-soft)}
.page-footer .muted{color:var(--muted);font-size:.82rem}
.muted{color:var(--muted)}

/* details/FAQ */
details.faq{border:1px solid var(--border);border-radius:var(--radius);margin:.7rem 0;
  background:var(--bg-elev);overflow:hidden}
details.faq summary{cursor:pointer;padding:14px 18px;font-weight:600;list-style:none;
  display:flex;justify-content:space-between;align-items:center}
details.faq summary::-webkit-details-marker{display:none}
details.faq summary::after{content:"+";color:var(--accent-1);font-size:1.3rem;font-weight:700}
details.faq[open] summary::after{content:"\2013"}
details.faq summary:hover{background:var(--bg-soft)}
details.faq .faq-body{padding:0 18px 16px;color:var(--text-soft)}
details.faq .faq-body p{margin:.4rem 0}

dl.gloss{margin:1rem 0}
dl.gloss dt{font-weight:700;margin-top:1rem;color:var(--text)}
dl.gloss dt .badge{margin-left:8px;font-weight:600}
dl.gloss dd{margin:.2rem 0 0;color:var(--text-soft);padding-left:0}