:root {
  --ratio-navy: #123b63;
  --ratio-blue: #1676c4;
  --ratio-teal: #18b7b0;
}

body::before {
  content: "RATIO  |  Teaching Lab";
  display: block;
  position: sticky;
  top: 0;
  z-index: 1000;
  padding: 13px clamp(20px, 5vw, 64px);
  color: white;
  background: var(--ratio-navy);
  border-bottom: 3px solid var(--ratio-teal);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 14px;
  font-weight: 700;
  letter-spacing: .08em;
}

.ratio-return {
  position: fixed;
  right: 20px;
  bottom: 20px;
  z-index: 1000;
  padding: 11px 16px;
  border-radius: 999px;
  color: white;
  background: var(--ratio-blue);
  box-shadow: 0 8px 24px rgba(18, 59, 99, .25);
  font: 600 13px/1.2 -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  text-decoration: none;
}

h1, h2, h3 { color: var(--ratio-navy); }
a { color: var(--ratio-blue); }
blockquote { border-left-color: var(--ratio-teal) !important; }

.ratio-contact {
  max-width: 980px;
  margin: 64px auto 36px;
  padding: 24px 28px;
  border: 1px solid rgba(18, 59, 99, .18);
  border-left: 5px solid var(--ratio-teal);
  border-radius: 12px;
  background: #f4f7fa;
  color: #172b3d;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.ratio-contact strong {
  display: block;
  margin-bottom: 6px;
  color: var(--ratio-navy);
  font-size: 18px;
}

.ratio-contact p { margin: 0; }
.ratio-contact a { font-weight: 700; }

@media (max-width: 720px) {
  .ratio-contact { margin: 48px 18px 84px; }
  .ratio-return { right: 14px; bottom: 14px; }
}