[Bug] theme file questions

### Bug Description

First of all, I am grateful for your product and the features you offer.
I wanted to customize the theme, I followed all the steps in your manual page, but no matter what I changed in the template, it was not reflected in the interface. I tried to understand the lines of code in the themes, but I am not sure I understood everything. For instance, I could not identify the background color line in the code, to change the transparency and color. I completely understood the codes for both, by the way, and I have no problems in writing the transparency or color code in those lines.
Any advise will be highly appreciated!

### How to Reproduce

Change the transparency and color codes in the json files, upload in the app the theme and apply it.

### Expected Behavior

The UI should change colors and transparencies for various elements

### Operating System

Windows

### AppFlowy Version(s)

latest, just downloaded today

### Screenshots

_No response_

### Additional Context

_No response_