Support About Postbit Background

[lorenz]

Hello everyone. I'm trying to learn the Xenforo forum system. I can add the postbit background using the DBTech shop plugin, but when I write a code to set the transparency in the custom css part, the postibt becomes completely transparent. How can I solve this problem? Ex: Screenshot

 

[Ala.R]

How can I solve this problem?

Enter the code you are using؟؟

 

[lorenz]

custom css part only
background: url(image-url);
opacity: 0.4;
I am using this codes. I don't know what css codes the plugin named DB tech uses.