sS hTopLeftCornerDiv(O contents, O... _) {
  ret hcss([[.topLeftCorner {
    position: absolute;
    left: 10px;
    top: 10px;
    opacity: .95;
    padding: 10px; 
    border: 1px solid black;
    background: white;
    color: black;
  }]])
    + div(contents, params_plusHTMLClass(_, "topLeftCorner"));
}