How to fill empty spaces in a non-standard PNG image?

Question

css

There is such a picture and as you can see it is non-standard cropped. According to the layout, it is slightly lightened by the overlay of a translucent gray bg and then the gray sections continue, which seem to merge with the bg picture, but if I put gray bg for all other sections, then bg on the png picture, where the empty spaces will be white.

Are there any options for these empty places in the picture to be gray and merge with subsequent sections?
UPD:
I don’t know why the option with background-color didn’t work out before, I probably used the wrong color, didn’t take into account the transparency of the white color.
in the class where the image is indicated through bg, I just added background-color: rgba(0, 0, 0, 0.31)

Answer 1

Use transparent instead of white