Overleaf/services/web/public/js/libs/pdfListView/HighlightsLayer.css

.plv-highlights-layer {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  overflow: hidden;
  pointer-events: none;
}
.plv-highlights-layer > div {
  display: block;
  position: absolute;
  pointer-events: auto;
  background-color: yellow;
  opacity: 0.4;
}