Hikashop Product Background Color

Hi,

Well, yes and no.
For png images, HikaShop does not add stripes since the png format supports transparency.
So the stripes are transparent for png images and thus what you see is actually the background color:
i.imgur.com/M3ebGs7.png
If you check that screenshot, you can see the grey and white check pattern for the image's stripes indicating the transparency.
And on the bottom right side, you can see a white background CSS rule applied to the area by your template's CSS.
So change that white color to black in your template's templates/shaper_spectrum/css/hikashop-black.css file
and you'll have the display you want:
i.imgur.com/Gdizcma.png
Ideally, you want to report the issue to your template provider. Maybe, they will recommend a better solution than directly modifying that CSS file.