/* ============ Variables & Base ============ */
:root{
  --bg:#0b1220; 
  --card:#ffffff; 
  --primary:#2563eb; 
  --accent:#16a34a; 
  --muted:#64748b; 
  --text:#0f172a;
}

*{ box-sizing: border-box; }
html{ scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--text);
  background: #f6f8fb;
  display: block; /* override old centering on body */
}

/* ============ Layout ============ */
.container { 
  max-width: 1000px; 
  width: 100%;
  margin: 0 auto; 
  padding: 1rem; 
}

/* Card-like sections */
section{
  background:#fff;
  border:1px solid #eef2f7;
  border-radius:12px;
  padding:1rem;
  margin:1rem 0;
  box-shadow:0 1px 0 rgba(15,23,42,.02);
}

/* Headings */
h1{ margin: 0.25rem 0 0.5rem; font-size: clamp(1.4rem, 3vw, 2rem); line-height:1.15; font-weight: 700; }
h2{ margin: 0.25rem 0 0.5rem; font-size: clamp(1.25rem, 2.5vw, 1.5rem); font-weight: 700; }
h3{ margin: 0.25rem 0 0.5rem; font-size: clamp(1.1rem, 2.2vw, 1.2rem); font-weight: 700; }

ul, ol{ padding-left: 1.25rem; }

/* ============ Hero ============ */
header.hero{
  background: radial-gradient(1200px 600px at 10% -10%, #e8f0ff, #f6f8fb 60%);
  border-bottom:1px solid #e5e7eb;
}
.hero p{ color: var(--muted); margin: 0 0 1rem; }
.cta-group{ display:flex; flex-wrap:wrap; gap:.5rem; margin-top:.75rem; }

/* ============ Buttons ============ */
a{ color:#0f172a; }
a:hover{ text-decoration: underline; }
.btn{
  display:inline-block;
  padding:.7rem 1rem;
  border-radius:.6rem;
  text-decoration:none;
  border:1px solid #dbe3f3;
  background:#fff;
  color:#0f172a;
  font-weight:600;
}
.btn.primary{ background:var(--primary); border-color:var(--primary); color:#fff; }

/* ============ Sticky TOC ============ */
nav.toc{
  position: sticky;
  top: 0;
  background:#fff;
  border-bottom:1px solid #eef2f7;
  z-index: 5;
}
nav.toc .wrap{
  max-width:1000px;
  margin:0 auto;
  padding:.5rem 1.25rem;
  display:flex;
  gap:.75rem;
  overflow:auto;
  scrollbar-width:thin;
}
nav.toc a{
  white-space:nowrap;
  color:#0f172a;
  text-decoration:none;
  padding:.4rem .6rem;
  border-radius:.5rem;
  border:1px solid #e5e7eb;
  background:#fff;
}

/* ============  Footer Disclaimer ============ */
footer {
  font-size: 0.75em;
  color: #666;
  margin-top: 8px;
  line-height: 1.4;
  text-align: center;
}