Closing because the documentation at https://webserver2.tecgraf.puc-rio.br/iup/en/elem/iupprogressbar.html specifies this feature to be Win/GTK only, and implementing these in HTML5 does not seem to be possible. Each browser chooses its own motif, and adding CSS background color has effect of covering over progress bar.
Closing because the documentation at https://webserver2.tecgraf.puc-rio.br/iup/en/elem/iupprogressbar.html specifies this feature to be Win/GTK only, and implementing these in HTML5 does not seem to be possible. Each browser chooses its own motif, and adding CSS background color has effect of covering over progress bar.