TIWEdit and HTML legend property

[valmeras]

I am using Intraweb 14.2.7 with Rad Studio Tokyo 10.2.3 (C++ Builder)
I would like to know how I can add a legend to a TIWEdit
I tried the solution below, but it does not work. The legend is not displayed

CSS definition
legend
{
  display: block;
  padding-left: 10px;
  border: none;
 background: none;
}

Then in my application
UnicodeString LegendText="username";
TIWEdit1->ExtraTagParams->Add("legend=" + LegendText);