:root {
  --bg: #fafeff;
  --brand: #004080;
  --ink: #474747;
  --accent: #ffd166;
  --soft: #e6f0fa;
  --shadow: 0 8px 30px rgba(6,22,38,0.08);
  --radius: 14px;
  --header-height: 84px; /* default header height */
  --header-vertical: 12px; /* new: vertical padding for header */
}

body {
  margin: 0;
  font-family: Inter, sans-serif;
  background: var(--bg);
  color: var(--ink);
}

/* --- Base Layout --- */
.page {
  min-height: 100vh;
  padding: 32px 20px 120px;
  display: flex;
  justify-content: center;
}

.site {
  width: 100%;
  max-width: 1100px;
}

.intro {
  margin: 0; /* header touches top and spans full width */
  padding: var(--header-vertical) 20px; /* use unified vertical padding */
  border-radius: 0;
  background: var(--brand); /* use brand color for header background */
  box-shadow: var(--shadow);
  position: sticky; /* keep header in flow to avoid overlapping */
  left: 0;
  right: 0;
  top: 0;
  min-height: auto; /* avoid forcing extra vertical space */
  display: flex;
  flex-direction: column; /* stack title and subtitle */
  align-items: center;
  justify-content: center;
  gap: 4px; /* reduced gap between title and tagline */
  z-index: 90;
}

/* constrain direct children so header content lines up with .site */
.intro > * {
  width: 100%;
  max-width: 1100px;
  text-align: center; /* center both title and tagline */
}

/* make heading and paragraph align and space properly */
.intro h1 {
  margin: 0 0 2px 0; /* small gap below title for tighter spacing */
  font-size: clamp(1.6rem, 6vw, 3rem);
  line-height: 1;
  font-family: 'Poppins', sans-serif;
  font-weight: 800;
  letter-spacing: -0.6px;
  color: var(--bg); /* white text on brand background */
  background: none; /* remove previous gradient */
  -webkit-background-clip: unset;
  -webkit-text-fill-color: unset;
  text-shadow: 0 4px 18px rgba(0,0,0,0.25); /* subtle dark shadow for contrast */
}

.intro p {
  margin: 0;
  color: var(--bg); /* white text for tagline */
  opacity: 0.95;
  font-size: 0.85rem; /* compact */
  line-height: 1.25;
  font-family: 'Poppins', sans-serif; /* tagline tone */
  font-weight: 600;
  letter-spacing: 2px;
  text-transform: uppercase;
  text-align: center;
}

/* stack heading and description and keep compact on small screens */
.intro h1, .intro p {
  display: block;
}

/* --- Desktop Layout --- */
.layout {
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: 20px;
}

/* --- TOC --- */
.toc {
  background: rgba(255,255,255,0.8);
  border-radius: var(--radius);
  padding: 14px;
  box-shadow: var(--shadow);
  position: sticky;
  top: 100px;
  z-index: 70;
}

.toc h3 {
  color: var(--brand);
  margin-top: 0;
}

.toc-category {
  margin-bottom: 8px;
}

.toc-category h4 {
  cursor: pointer;
  margin: 0;
  background: var(--soft);
  padding: 8px;
  border-radius: 8px;
  color: var(--brand);
  font-size: 14px;
}

.toc-items {
  display: none;
  margin-left: 12px;
}

.toc-items.open {
  display: block;
}

.toc-item {
  padding: 6px 8px;
  border-radius: 6px;
  cursor: pointer;
}

.toc-item:hover {
  background: var(--soft);
}

/* --- Cards --- */
.cards {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.card {
  background: #fff;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 16px;
}

.q {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 8px;
}

.q h2 {
  color: var(--brand);
  margin: 0;
  font-size: 1.25rem;
}

.a {
  margin-top: 10px;
  line-height: 1.6;
}

.refs {
  margin-top: 10px;
  padding: 6px;
  background: var(--soft);
  border-radius: 8px;
  font-size: 0.85rem;
}

.ref-item {
  font-size: 0.7rem;
  margin-bottom: 4px;
}

.term {
  font-weight: 600;
  color: var(--brand);
  font-size: 0.75rem;
  line-height: 2;
}

.tags {
  margin-top: 10px;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.tag {
  background: var(--soft);
  border-radius: 999px;
  padding: 4px 10px;
  font-size: 12px;
  cursor: pointer;
}

/* --- Sticky search footer --- */
.sticky-search {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 12px;
  display: flex;
  justify-content: center;
  z-index: 95;
}

.search-panel {
  width: min(calc(100% - 32px), 960px);
  background: transparent; /* fully transparent footer background */
  border-radius: 25px; /* increased rounding */
  box-shadow: none; /* remove shadow for no background */
  padding: 8px 10px;
  display: flex;
  gap: 8px;
  align-items: center;
}

.search-input {
  flex: 1;
  border: 1px solid rgba(6,22,38,0.06);
  padding: 10px 12px;
  border-radius: 999px; /* pill */
  font-size: 0.95rem;
}

.search-btn {
  background: var(--brand);
  color: white;
  border: none;
  padding: 8px 12px;
  border-radius: 999px; /* pill */
  cursor: pointer;
  font-weight: 600;
}

@media (max-width: 480px) {
  .search-panel { padding: 6px 8px; gap: 6px; border-radius: 16px; }
  .search-input { padding: 8px 10px; }
  .search-btn { padding: 7px 10px; }
}

/* --- bottom fade behind footer */
.bottom-fade {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  height: 150px; /* height of the fade area */
  pointer-events: none;
  z-index: 90; /* below the sticky-search (95) so footer sits above */
  background: linear-gradient(to top, var(--bg), rgba(250,254,255,1), rgba(250,254,255,0));
}

@media (max-width: 480px) {
  .bottom-fade { height: 160px; }
}

/* --- Responsive Styles --- */
@media (max-width: 820px) {
  :root { --header-height: 72px; --header-vertical: 10px; }

  .layout {
    grid-template-columns: 1fr;
  }

  aside {
    order: -1;
    position: relative;
  }

  .toc {
    position: relative;
    top: unset;
    margin-bottom: 20px;
  }

  .intro {
    padding: var(--header-vertical) 16px;
    gap: 0px; /* remove gap for tighter stacking on tablet/iPad */
  }

  .intro > * {
    padding: 6px 0;
  }

  /* ensure no extra margins between title and tagline */
  .intro h1 {
    margin-bottom: 0;
    line-height: 1.02;
  }

  .intro p {
    margin-top: 0;
  }

  .card {
    padding: 14px;
  }

  .q h2 {
    font-size: 1.1rem;
  }

  .site {
    padding: 0 12px;
  }
}

@media (max-width: 480px) {
  :root { --header-height: 64px; --header-vertical: 10px; }

  .intro {
    padding: var(--header-vertical) 12px;
    flex-direction: column;
    align-items: flex-start;
    justify-content: flex-start; /* keep content near the top */
    gap: 0px; /* remove gap on small mobile */
  }

  .intro h1 {
    font-size: clamp(2rem, 9.5vw, 3rem);
    letter-spacing: -0.4px;
    line-height: 1.02;
    text-shadow: 0 10px 30px rgba(0,64,128,0.12);
    margin: 0 0 0 0; /* remove bottom margin */
  }

  .intro p {
    display: block;
    font-size: 0.82rem; /* slightly smaller on very small screens */
    opacity: 0.95;
    margin-top: 0; /* remove top margin */
    line-height: 1.25; /* slightly tighter line-height */
    text-align: center;
  }

  body {
    font-size: 15px;
  }

  .card {
    padding: 12px;
  }

  .q h2 {
    font-size: 1rem;
  }

  .toc h3 {
    font-size: 16px;
  }

  .site {
    padding: 0 10px;
  }

  /* Reduce top spacing so header and hero content sit closer together */
  .page {
    padding: 20px;
  }
}