/* ===== Colors (dark blue accent) ===== */
:root {
  color-scheme: light;
  --bg: #fbfcfd;
  --surface: #ffffff;
  --text: #1a1f2b;
  --muted: #566070;
  --accent: #1e3a8a;
  --accent-soft: #c9d6ee;
  --line: #dfe4ec;
}

@media (prefers-color-scheme: dark) {
  :root {
    color-scheme: dark;
    --bg: #13161d;
    --surface: #1c2029;
    --text: #e9ecf2;
    --muted: #a3abb9;
    --accent: #8fb4f0;
    --accent-soft: #22345a;
    --line: #2f3542;
  }
}

/* ===== Base ===== */
*, *::before, *::after { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Public Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  font-size: 1.0625rem;
  line-height: 1.6;
}

h1, h2 {
  font-family: "Spectral", Georgia, "Times New Roman", serif;
  font-weight: 700;
  line-height: 1.15;
  margin: 0 0 0.75rem;
}

h2 { font-size: clamp(1.6rem, 3vw, 2.1rem); }

p { margin: 0 0 1rem; }

a { color: var(--accent); text-underline-offset: 3px; }

img { max-width: 100%; display: block; }

:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 3px;
}

/* ===== Layout ===== */
.wrap {
  max-width: 44rem;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.wrap-wide {
  max-width: 72rem;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.wrap-inner { max-width: 41rem; margin: 0 auto; }

.section { padding-top: 4rem; }

.note { color: var(--muted); font-size: 0.95rem; }

/* ===== Hero ===== */
.hero {
  padding: 5rem 0 3.5rem;
  border-bottom: 1px solid var(--line);
  /* faint ridge-line echoing the density plots */
  background:
    radial-gradient(ellipse 18% 60% at 78% 100%, var(--accent-soft) 0 60%, transparent 61%),
    radial-gradient(ellipse 10% 85% at 88% 100%, var(--accent-soft) 0 60%, transparent 61%),
    radial-gradient(ellipse 7% 45% at 96% 100%, var(--accent-soft) 0 60%, transparent 61%),
    var(--bg);
}

@media (max-width: 720px) {
  .hero { background: var(--bg); padding-top: 3.5rem; }
}

.byline {
  color: var(--accent);
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.hero h1 {
  font-size: clamp(2.6rem, 8vw, 4.75rem);
  letter-spacing: -0.02em;
}

.lede {
  font-size: 1.2rem;
  color: var(--muted);
  max-width: 36rem;
}

.primary-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 2rem;
}

.btn {
  display: inline-block;
  padding: 0.75rem 1.4rem;
  border-radius: 999px;
  font-weight: 600;
  text-decoration: none;
  border: 2px solid var(--accent);
  transition: background-color 0.15s, color 0.15s;
}

.btn-solid { background: var(--accent); color: var(--bg); }
.btn-solid:hover { background: transparent; color: var(--accent); }

.btn-outline { color: var(--accent); }
.btn-outline:hover { background: var(--accent); color: var(--bg); }

/* ===== Slides embed (16:9) ===== */
.embed {
  position: relative;
  aspect-ratio: 16 / 9;
  border: 1px solid var(--line);
  border-radius: 6px;
  overflow: hidden;
  background: var(--surface);
  margin-bottom: 0.75rem;
}

.embed iframe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

/* ===== Figures ===== */
.figure-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 22rem), 1fr));
  gap: 2rem;
  margin-top: 1.5rem;
}

.fig { margin: 0; }

.fig-open {
  display: block;
  width: 100%;
  padding: 0.75rem;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #ffffff; /* graphs have white backgrounds; keep them on white */
  cursor: zoom-in;
}

.fig-open:hover { border-color: var(--accent); }

.fig figcaption {
  margin-top: 0.75rem;
  color: var(--muted);
  font-size: 0.95rem;
}

.fig figcaption strong {
  display: block;
  color: var(--text);
}

/* ===== Lightbox ===== */
#lightbox {
  max-width: min(92vw, 70rem);
  padding: 1rem;
  border: none;
  border-radius: 8px;
  background: #ffffff;
  color: #1a1f2b;
}

#lightbox::backdrop { background: rgba(12, 17, 30, 0.75); }

#lightbox img { width: 100%; height: auto; }

.lightbox-caption { margin: 0.75rem 0 0; font-size: 0.95rem; }

.lightbox-close {
  position: absolute;
  top: 0.4rem;
  right: 0.6rem;
  font-size: 1.75rem;
  line-height: 1;
  border: none;
  background: none;
  color: #1a1f2b;
  cursor: pointer;
}

/* ===== Footer ===== */
.footer {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  margin-top: 5rem;
  padding-top: 1.5rem;
  padding-bottom: 2rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.95rem;
}

.footer p { margin: 0; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .btn { transition: none; }
}

/* ===== About findings ===== */
.findings { padding-left: 1.25rem; margin: 0 0 1rem; }
.findings li { margin-bottom: 0.6rem; }