:root{
  --primary:#1d4ed8;
  --secondary:#1e3a8a;
  --accent:#84cc16;
  --bg:#ffffff;
  --surface:#eff6ff;
  --surface-alt:#dbeafe;
  --text:#1e3a8a;
  --muted:#5f6e7d;
  --border:#bfdbfe;
  --row-alt:#eff6ff;
  --radius:12px;
}
*,*::before,*::after{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:17px;
}
img{max-width:100%;height:auto;display:block}
a{color:var(--primary);text-decoration:underline;text-underline-offset:3px}
a:hover{color:var(--secondary)}
.container{max-width:1120px;margin:0 auto;padding:0 20px}

/* Header */
.site-header{
  position:sticky;top:0;z-index:100;
  background:linear-gradient(135deg,var(--primary),var(--secondary));
  color:#fff;
  box-shadow:0 2px 12px rgba(30,58,138,.18);
}
.site-header .container{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:14px 20px}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:#fff;font-weight:700}
.brand img{width:40px;height:40px}
.brand span{font-size:1.15rem;letter-spacing:.2px}
.site-nav ul{list-style:none;display:flex;flex-wrap:wrap;gap:6px;margin:0;padding:0}
.site-nav a{
  color:#fff;text-decoration:none;padding:8px 12px;border-radius:999px;
  font-weight:500;font-size:.95rem;
  transition:background .15s;
}
.site-nav a:hover{background:rgba(255,255,255,.14)}
.site-nav a.active{background:var(--accent);color:var(--secondary)}

/* Hero */
.hero{
  background:linear-gradient(135deg,var(--primary),var(--secondary));
  color:#fff;padding:56px 0 64px;
  position:relative;overflow:hidden;
}
.hero::after{
  content:"";position:absolute;right:-80px;bottom:-80px;
  width:280px;height:280px;border-radius:50%;
  background:radial-gradient(circle,var(--accent) 0%,transparent 70%);
  opacity:.35;pointer-events:none;
}
.hero h1{font-size:2.3rem;line-height:1.15;margin:0 0 12px;max-width:900px}
.hero .byline{color:rgba(255,255,255,.9);margin:0 0 22px;font-size:.95rem}
.hero .lede{max-width:820px;font-size:1.08rem;color:rgba(255,255,255,.96)}
.cta-row{margin-top:24px;display:flex;gap:12px;flex-wrap:wrap}
.btn{
  display:inline-block;padding:12px 22px;border-radius:999px;
  font-weight:600;text-decoration:none;font-size:.98rem;
  transition:transform .15s,box-shadow .15s;
}
.btn-primary{background:var(--accent);color:var(--secondary)}
.btn-primary:hover{transform:translateY(-1px);box-shadow:0 6px 18px rgba(132,204,22,.35)}
.btn-ghost{background:transparent;color:#fff;border:2px solid rgba(255,255,255,.7)}
.btn-ghost:hover{background:rgba(255,255,255,.12)}

/* Content sections */
main{padding:40px 0 60px}
section{margin:0 0 44px}
h2{
  font-size:1.55rem;line-height:1.25;
  margin:44px 0 16px;
  padding:10px 16px;
  border-left:5px solid var(--accent);
  background:var(--surface);
  border-radius:0 var(--radius) var(--radius) 0;
  color:var(--secondary);
}
h3{font-size:1.2rem;margin:26px 0 10px;color:var(--secondary)}
p{margin:0 0 14px}

/* Table of contents */
.toc{
  background:var(--surface-alt);
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:18px 22px;
  margin:24px 0 32px;
}
.toc h2{
  border:none;background:none;padding:0;margin:0 0 10px;
  font-size:1.15rem;color:var(--secondary);
}
.toc ol{margin:0;padding-left:22px;columns:2;column-gap:28px}
.toc ol li{margin:4px 0;break-inside:avoid}
.toc a{color:var(--secondary);text-decoration:none}
.toc a:hover{text-decoration:underline}

/* Lists */
ul{list-style:none;padding-left:0}
ul li{
  position:relative;padding:4px 0 4px 26px;
}
ul li::before{
  content:"➤";position:absolute;left:0;top:4px;
  color:var(--accent);font-weight:700;
}
ol{counter-reset:step;list-style:none;padding-left:0}
ol li{
  counter-increment:step;
  position:relative;padding:6px 0 6px 46px;margin:8px 0;
}
ol li::before{
  content:counter(step);
  position:absolute;left:0;top:4px;
  width:32px;height:32px;border-radius:50%;
  background:linear-gradient(135deg,var(--primary),var(--secondary));
  color:#fff;font-weight:700;
  display:flex;align-items:center;justify-content:center;
  font-size:.9rem;
}
.toc ol{counter-reset:none}
.toc ol li{counter-increment:none;padding:4px 0}
.toc ol li::before{display:none}

/* Tables */
.table-wrap{overflow-x:auto;margin:18px 0;border-radius:var(--radius);border:1px solid var(--border)}
table{width:100%;border-collapse:collapse;background:var(--bg);min-width:520px}
thead th{
  background:linear-gradient(135deg,var(--primary),var(--secondary));
  color:#fff;text-align:left;padding:12px 14px;font-weight:600;
}
tbody td{padding:11px 14px;border-top:1px solid var(--border);vertical-align:top}
tbody tr:nth-child(even){background:var(--row-alt)}

/* FAQ accordion */
details{
  background:var(--surface);
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:0;
  margin:10px 0;
  overflow:hidden;
}
details summary{
  cursor:pointer;list-style:none;
  padding:14px 46px 14px 18px;
  font-weight:600;color:var(--secondary);
  position:relative;
}
details summary::-webkit-details-marker{display:none}
details summary::after{
  content:"▼";position:absolute;right:18px;top:50%;
  transform:translateY(-50%);color:var(--accent);
  transition:transform .2s;font-size:.85rem;
}
details[open] summary::after{transform:translateY(-50%) rotate(180deg)}
details[open] summary{background:var(--surface-alt)}
details p{padding:6px 18px 16px;margin:0}

/* Author box */
.author-box{
  display:flex;gap:18px;align-items:flex-start;
  background:linear-gradient(135deg,var(--surface),var(--surface-alt));
  border:1px solid var(--border);
  border-left:5px solid var(--accent);
  border-radius:var(--radius);
  padding:20px;margin:36px 0 20px;
}
.author-box img{width:80px;height:80px;border-radius:50%;background:var(--bg);border:2px solid var(--border)}
.author-name{font-weight:700;color:var(--secondary);margin:0 0 2px}
.author-role{color:var(--muted);margin:0 0 8px;font-size:.9rem}
.author-bio{margin:0;color:var(--text);font-size:.95rem}

/* Callout / info */
.callout{
  background:var(--surface-alt);
  border-left:4px solid var(--primary);
  border-radius:0 var(--radius) var(--radius) 0;
  padding:14px 18px;margin:18px 0;
}
.callout strong{color:var(--secondary)}

/* Content SVG figures */
figure.diagram{margin:24px 0;padding:16px;background:var(--surface);border-radius:var(--radius);border:1px solid var(--border)}
figure.diagram svg{width:100%;height:auto;max-height:340px}
figure.diagram figcaption{font-size:.9rem;color:var(--muted);margin-top:8px;text-align:center}

/* Footer */
.site-footer{
  background:var(--secondary);color:rgba(255,255,255,.9);
  padding:36px 0 22px;margin-top:60px;
  font-size:.92rem;
}
.site-footer .container{display:grid;grid-template-columns:1fr;gap:22px}
.site-footer a{color:#fff}
.footer-cols{display:grid;grid-template-columns:1fr;gap:22px}
.footer-cols h3{color:var(--accent);margin:0 0 8px;font-size:1rem}
.footer-cols ul{margin:0;padding:0}
.footer-cols ul li{padding:3px 0 3px 20px}
.footer-cols ul li::before{content:"›";color:var(--accent)}
.footer-legal{border-top:1px solid rgba(255,255,255,.15);padding-top:14px;color:rgba(255,255,255,.7);font-size:.85rem}

/* Byline in body */
.byline{
  color:var(--muted);font-size:.9rem;margin:0 0 20px;
}
.byline strong{color:var(--secondary)}

/* Utility */
.wide{max-width:1120px}
.small{font-size:.9rem;color:var(--muted)}
.tag{
  display:inline-block;background:var(--accent);color:var(--secondary);
  padding:2px 10px;border-radius:999px;font-size:.78rem;font-weight:600;
  margin-right:6px;
}

/* Responsive */
@media (min-width:700px){
  .hero{padding:72px 0 80px}
  .hero h1{font-size:2.8rem}
  .site-footer .container{grid-template-columns:1.4fr 2fr}
  .footer-cols{grid-template-columns:repeat(3,1fr)}
}
@media (min-width:980px){
  body{font-size:17.5px}
  .hero h1{font-size:3.1rem}
  h2{font-size:1.7rem}
}
@media (max-width:700px){
  .toc ol{columns:1}
  .site-header .container{flex-direction:column;align-items:flex-start}
  .site-nav ul{justify-content:flex-start}
}

/* 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}
a:focus-visible,button:focus-visible,summary:focus-visible{outline:3px solid var(--accent);outline-offset:2px}
@media (prefers-reduced-motion: reduce){*,*::before,*::after{transition-duration:.01ms !important;animation-duration:.01ms !important}}