cobexer/html2canvas — comment on commit 044b612d6ed91ec39d28749085a41ec9be11e451
File:  line 0
By niklasvh:

That probably would work for many cases, but what if no background details are defined, i.e. it is transparent, wouldn't that just result in the same issue as previously?

I doubt you can with Javascript even find out what the users default browser background bgcolor is, unless it is defined into the CSS and at the same time, I would presume the users who don't have it as white are such a minority that it wouldn't be of that big of an importance at this point.