:root {
  --text: #2c3e50;
  --bg: #f8f9fa;
  --head: #1a1a1a;
  --link: #0069d9;
}

/* Base */
html { scroll-behavior: smooth; }
html, body { height: 100%; }
body {
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.7;
  color: var(--text);
  background-color: var(--bg);
  margin: 0;
  padding: 2rem;
}
main { max-width: 900px; margin: auto; }
a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }
p { margin: 1rem 0; }

/* Type */
h1, h2, h3, h4 {
  font-weight: 600;
  color: var(--head);
  margin-top: 2rem;
  line-height: 1.25;
}
h1 { font-size: clamp(1.8rem, 2.5vw, 2.4rem); }
h2 { font-size: clamp(1.4rem, 2vw, 1.8rem); }
.lead { font-size: 1.05rem; }
.muted { color: #5c6b77; }

/* Sections/cards/grid */
.section { scroll-margin-top: 72px; }
.card {
  background: #fff;
  border: 1px solid rgba(0,0,0,.06);
  border-radius: 12px;
  padding: 1.25rem 1.25rem;
  box-shadow: 0 1px 2px rgba(0,0,0,.04);
  margin: 1rem 0;
}
.grid { display: grid; grid-template-columns: 1fr; gap: 1rem; }
@media (min-width: 720px) {
  .grid { grid-template-columns: repeat(2, 1fr); }
}
.center { text-align: center; }

/* ===== Header / Navigation (single, fixed) ===== */
.site-header {
  position: fixed;       /* keep visible while scrolling */
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: #f8f9fa;
  border-bottom: 1px solid #eee;
  box-shadow: 0 2px 5px rgba(0,0,0,.06);
}

.site-nav {
  max-width: 900px;
  margin: 0 auto;
  padding: .75rem 0;
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  justify-content: center;
}

.site-nav a {
  color: var(--link);    /* blue, same as content links */
  text-decoration: none;
  transition: color .2s ease;
}
.site-nav a:hover { text-decoration: underline; }

/* Spacer so content isn’t hidden behind fixed menu */
.menu-spacer { height: 72px; }
@media (max-width: 640px) { .menu-spacer { height: 96px; } }

/* Hero */
.hero {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto 1rem auto;
  height: clamp(180px, 30vw, 340px);
  border-radius: 14px;
  overflow: hidden;
  background: #e9ecef url('20pln-header-1600x480.jpg') center / cover no-repeat;
  position: relative;
  box-shadow: 0 6px 20px rgba(0,0,0,.12);
}
.hero::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, rgba(248,249,250,.28), rgba(248,249,250,0));
  pointer-events: none;
}

/* Tables */
.table { width:100%; border-collapse: collapse; }
.table th, .table td { padding: .6rem .75rem; border-top: 1px solid rgba(0,0,0,.08); vertical-align: top; }
.table thead th { border-bottom: 2px solid rgba(0,0,0,.12); text-align:left; }

/* Figures & images */
figure { margin: 2rem 0; } /* space above+below */
figure img { display:block; height:auto; margin: 0 auto; border-radius: 8px; box-shadow: 0 2px 12px rgba(0,0,0,.12); }
.img-full { max-width:100%; }
.img-90 { max-width:90%; }
.img-75 { max-width:75%; }
.mt-05 { margin-top:.5rem; }
.mt-10 { margin-top:1rem; }

figcaption {
  margin-top: .9rem;
  line-height: 1.7;
  font-size: 1rem;
  color: #47515b;
}
figure .muted { color: #47515b; }

/* When figures stack, add extra space between them */
figure + figure { margin-top: 2.5rem; }
figure + p { margin-top: 1.25rem; }

/* Mystery box */
.mystery-box {
  padding:1rem;
  border:1px dashed #aaa;
  border-radius:8px;
  background:#f9f9f9;
  text-align:center;
}

/* Footer */
footer {
  margin-top: 3rem;
  font-size: .95rem;
  color: #5c6b77;
}

/* Back to top button */
.back-to-top {
  position: fixed;
  right: 20px;
  bottom: 24px;
  padding: 0.6rem 0.9rem;
  border-radius: 999px;
  border: 1px solid rgba(0,0,0,.12);
  background: #ffffff;
  color: #1a1a1a;
  font-weight: 600;
  box-shadow: 0 4px 12px rgba(0,0,0,.12);
  cursor: pointer;
  opacity: 0;
  pointer-events: none;
  transition: opacity .2s ease, transform .15s ease;
}
.back-to-top:hover { transform: translateY(-2px); }

.site-nav a.visited {
  color: #6c757d;
  font-weight: 600;
  text-decoration: underline;
}

html {
  scroll-behavior: smooth;
}

[id] {
  scroll-margin-top: 80px; /* match your fixed header height */
}
.site-footer{
  margin-top:48px;
  padding:16px 0 32px;
  border-top:1px solid #e6e6e6;
  color:#6b6b6b;
  font-size:.9rem;
}
.site-footer a{ color:inherit; text-decoration:underline }
.site-footer a:hover{ text-decoration:none }