Form fields background opacty

[hole_digger]

Hello. I need some help with form fields background. Empty fields should be somehow emphased. In adobe program setting border color to red is enough. When someone opens pdf in a browser the border dont show. I need to find some alternative like setting background color whch has to be with opacity (i hope its possible) or any other way. 

[JR Boulay]

A background colour can be defined in a form field, but opacity will only be managed after the advent of PDF 2.0.

[hole_digger]

So theres no way to set opacity of the background color so far right?

[JR Boulay]

Yes.

[hole_digger]

Thats not exactly what im trying to do. I have a button that checks all fields and if any are empty then they should be emphasized. And i need to find a way to do this on website, since setting border color doesnt work and setting background color without some opacity/transparency wont really work.

[JR Boulay]

"Here’s how:"

The OP talks about opacity/transparency, not about the highlight color.