CSS opacity issue

[alijanik]

I am creating an HTML and then converting it to a PDF file by using the below line:
PdfConverterExtension.exportToPdf(byteArrayOutputStream, htmlWithCss, "", BaseRendererBuilder.TextDirection.LTR);

I have a watermark CSS in my HTML and I tested both of the following CSS for transparency:

• color: rgba(211,211,211,0.1);
• color: #D3D3D3; opacity: 0.1;

But unfortunately, none of them works. I think the converter does not support it!
Do you have any idea?