/* Give observations most of the screen, independently of header height. */
.viewer:not(:fullscreen):not(.expanded) .image-area {
  height: clamp(480px, 75dvh, 1100px);
}
@media (min-width: 1001px) {
  main { padding: 20px 24px; }
  .section-heading { margin-bottom: 14px; }
  .toolbar { margin-bottom: 14px; }
}
@media (max-width: 720px) {
  .viewer:not(:fullscreen):not(.expanded) .image-area {
    height: clamp(260px, 72vw, 540px);
  }
}
 .period-selector{display:flex;gap:8px;flex-wrap:wrap;width:100%;margin-bottom:8px}
 .period-selector button[aria-pressed="true"]{background:#73ddcb;color:#09232c;border-color:#73ddcb}
 #periodCoverage{width:100%;margin:0 0 12px;line-height:1.5}