ns4 = (document.layers)? true:false
  ie4 = (document.all)? true:false

  if (ns4||ie4) document.writeln('<DIV ID="bulge"><IMG SRC="bulge.gif" WIDTH=49 HEIGHT=148 BORDER=0></DIV>')
  else alert("You must have Netscape 4.0 or Internet Explorer 4.0\nto view the examples in this site.")

I remember using layers. I was in primary school at the time.