:root{
  --primary:#1e40af;
  --secondary:#1e3a8a;
  --accent:#b45309;
  --bg:#ffffff;
  --surface:#eff6ff;
  --surface-alt:#dbeafe;
  --text:#1e3a8a;
  --muted:#5e6d7c;
  --border:#bfdbfe;
  --row-alt:#eff6ff;
  --radius:6px;
  --shadow:0 4px 14px rgba(30,58,138,.08);
  --shadow-lg:0 12px 32px rgba(30,58,138,.14);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Oxygen,Ubuntu,Cantarell,"Helvetica Neue",Arial,sans-serif;
  color:var(--text);
  background:var(--bg);
  line-height:1.65;
  font-size:16.5px;
  -webkit-font-smoothing:antialiased;
}
a{color:var(--primary);text-decoration:underline;text-underline-offset:2px}
a:hover{color:var(--accent)}
img,svg{max-width:100%;height:auto;display:block}

/* Header */
.site-header{
  position:sticky;top:0;z-index:20;
  background:linear-gradient(135deg,var(--primary) 0%,var(--secondary) 100%);
  box-shadow:var(--shadow);
}
.site-header .inner{
  max-width:1120px;margin:0 auto;padding:.75rem 1.1rem;
  display:flex;align-items:center;justify-content:space-between;gap:1rem;flex-wrap:wrap;
}
.brand{display:flex;align-items:center;gap:.65rem;color:#fff;text-decoration:none;font-weight:700}
.brand img{width:36px;height:36px;background:#fff;border-radius:8px;padding:3px}
.brand span{font-size:1.02rem;letter-spacing:.2px}
nav.primary ul{list-style:none;margin:0;padding:0;display:flex;flex-wrap:wrap;gap:.15rem}
nav.primary a{
  color:#fff;text-decoration:none;
  padding:.5rem .75rem;border-radius:var(--radius);
  font-size:.94rem;transition:background .18s;
}
nav.primary a:hover{background:rgba(255,255,255,.14)}

/* Hero */
.hero{
  background:linear-gradient(135deg,var(--primary) 0%,var(--secondary) 55%,#3b3193 100%);
  color:#fff;padding:3rem 1.1rem 3.5rem;
  border-bottom:4px solid var(--accent);
}
.hero .inner{max-width:960px;margin:0 auto}
.hero h1{
  font-size:clamp(1.75rem,3.6vw,2.7rem);line-height:1.18;
  margin:0 0 .6rem;color:#fff;font-weight:800;letter-spacing:-.01em;
}
.byline{color:#dbeafe;font-size:.95rem;margin:0 0 1.3rem}
.byline strong{color:#fff}
.hero p.lede{font-size:1.06rem;color:#eff6ff;margin:0 0 1.5rem;max-width:70ch}
.cta-row{display:flex;flex-wrap:wrap;gap:.6rem;margin-top:1rem}
.cta{
  display:inline-block;padding:.7rem 1.15rem;border-radius:var(--radius);
  font-weight:600;text-decoration:none;font-size:.98rem;transition:transform .12s;
}
.cta.primary{background:var(--accent);color:#fff}
.cta.primary:hover{background:#92400e;color:#fff;transform:translateY(-1px)}
.cta.ghost{border:1.5px solid #dbeafe;color:#fff;background:transparent}
.cta.ghost:hover{background:rgba(255,255,255,.1);color:#fff}

/* Main layout */
main{max-width:840px;margin:0 auto;padding:2.2rem 1.1rem 3rem}
main.wide{max-width:960px}

/* H2 with accent border */
h2{
  font-size:1.55rem;margin:2.4rem 0 .9rem;
  padding:.55rem 0 .55rem .95rem;
  border-left:4px solid var(--accent);
  background:var(--surface);
  color:var(--secondary);
  border-radius:0 var(--radius) var(--radius) 0;
  scroll-margin-top:80px;
}
h3{font-size:1.18rem;margin:1.6rem 0 .6rem;color:var(--secondary)}
p{margin:0 0 1rem}

/* ToC */
nav.toc{
  background:var(--surface-alt);
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:1.1rem 1.25rem;margin:1.5rem 0 2rem;
}
nav.toc h2{
  all:unset;display:block;font-weight:700;color:var(--secondary);
  font-size:1.05rem;margin-bottom:.6rem;
}
nav.toc ol{margin:0;padding-left:1.4rem;columns:2;column-gap:1.6rem}
nav.toc li{margin:.22rem 0;break-inside:avoid}
nav.toc a{color:var(--primary)}
@media (max-width:640px){nav.toc ol{columns:1}}

/* Lists */
ul.arrow{list-style:none;padding-left:0}
ul.arrow li{position:relative;padding-left:1.5rem;margin:.35rem 0}
ul.arrow li::before{
  content:"\25B8";position:absolute;left:0;top:0;
  color:var(--accent);font-weight:700;
}
ol.circle{list-style:none;padding-left:0;counter-reset:cir}
ol.circle li{position:relative;padding-left:2.3rem;margin:.55rem 0;counter-increment:cir}
ol.circle li::before{
  content:counter(cir);
  position:absolute;left:0;top:.05rem;
  width:1.7rem;height:1.7rem;border-radius:50%;
  background:linear-gradient(135deg,var(--primary),var(--secondary));
  color:#fff;display:grid;place-items:center;font-weight:700;font-size:.85rem;
}

/* Tables */
.table-wrap{overflow-x:auto;margin:1.3rem 0;border-radius:var(--radius);box-shadow:var(--shadow)}
table{width:100%;border-collapse:collapse;background:#fff;min-width:520px}
thead th{
  background:linear-gradient(135deg,var(--primary),var(--secondary));
  color:#fff;text-align:left;padding:.7rem .8rem;font-weight:600;font-size:.94rem;
}
tbody td{padding:.6rem .8rem;border-bottom:1px solid var(--border);font-size:.95rem}
tbody tr:nth-child(even) td{background:var(--row-alt)}
tbody tr:last-child td{border-bottom:none}

/* FAQ */
details{
  border:1px solid var(--border);border-radius:var(--radius);
  margin:.55rem 0;background:#fff;transition:box-shadow .15s;
}
details[open]{box-shadow:var(--shadow)}
details summary{
  cursor:pointer;padding:.85rem 1rem;font-weight:600;color:var(--secondary);
  list-style:none;display:flex;justify-content:space-between;align-items:center;gap:.7rem;
}
details summary::-webkit-details-marker{display:none}
details summary::after{
  content:"\25BC";color:var(--accent);font-size:.8rem;
  transition:transform .2s;flex-shrink:0;
}
details[open] summary::after{transform:rotate(180deg)}
details .a{padding:0 1rem 1rem;color:var(--text)}

/* Author box */
.author-box{
  margin:2.6rem 0 .8rem;
  background:linear-gradient(135deg,var(--surface-alt),var(--surface));
  border:1px solid var(--border);border-radius:var(--radius);
  padding:1.2rem 1.3rem;display:flex;gap:1.1rem;align-items:flex-start;
  box-shadow:var(--shadow);
}
.author-box img{width:76px;height:76px;border-radius:50%;background:#fff;flex-shrink:0}
.author-box .who{margin:0 0 .25rem;font-weight:700;color:var(--secondary)}
.author-box .role{color:var(--accent);font-size:.9rem;margin:0 0 .5rem;font-weight:600}
.author-box p{margin:0;font-size:.95rem;color:var(--text)}

/* Figures */
figure{margin:1.6rem 0;text-align:center}
figure svg{margin:0 auto;max-width:100%}
figcaption{color:var(--muted);font-size:.88rem;margin-top:.4rem;font-style:italic}

/* Callout */
.callout{
  background:var(--surface);border-left:4px solid var(--primary);
  border-radius:0 var(--radius) var(--radius) 0;
  padding:1rem 1.2rem;margin:1.4rem 0;font-size:.97rem;
}
.callout.warn{border-left-color:var(--accent);background:#fef3c7}
.callout strong{color:var(--secondary)}

/* Footer */
footer.site{
  background:linear-gradient(135deg,var(--secondary) 0%,#0f172a 100%);
  color:#dbeafe;margin-top:3rem;padding:2.2rem 1.1rem 1.5rem;
}
footer.site .inner{max-width:1120px;margin:0 auto;display:grid;gap:1.5rem;grid-template-columns:1.4fr 1fr 1fr}
footer.site h3{margin:0 0 .55rem;color:#fff;font-size:1rem}
footer.site a{color:#dbeafe;text-decoration:none;font-size:.93rem}
footer.site a:hover{color:#fff;text-decoration:underline}
footer.site ul{list-style:none;margin:0;padding:0}
footer.site ul li{margin:.25rem 0}
footer.site .credits{
  border-top:1px solid rgba(255,255,255,.12);
  margin-top:1.5rem;padding-top:1rem;font-size:.85rem;color:#bfdbfe;text-align:center;
}
@media (max-width:700px){footer.site .inner{grid-template-columns:1fr}}

/* Skip link */
.skip{position:absolute;left:-9999px;top:0}
.skip:focus{left:.5rem;top:.5rem;background:var(--accent);color:#fff;padding:.5rem 1rem;border-radius:var(--radius);z-index:99}

/* Utility */
.small{font-size:.9rem;color:var(--muted)}
hr{border:none;border-top:1px solid var(--border);margin:2.2rem 0}

/* a11y additions */
.skip-link{position:absolute;left:-9999px;top:0;background:var(--primary);color:#fff;padding:10px 16px;border-radius:4px;z-index:1000;text-decoration:none;font-weight:700}
.skip-link:focus{left:12px;top:12px}
@media (prefers-reduced-motion: reduce){*,*::before,*::after{transition-duration:.01ms !important;animation-duration:.01ms !important}}